Optical fiber cable, and systems and methods for distributing ultra-high power using optical fiber cable

Abstract

To provide an optical fiber cable and an integrated optical fiber power supply system capable of efficiently transmitting ultra-high power over long distances with significantly low loss.SOLUTION: Embodiments include an optical fiber cable comprising: a length extending between a first end and a second end; a central cooling tube; a plurality of optical fibers disposed radially around the cooling tube, each optical fiber comprising a fiber core and a cladding disposed around the fiber core; an outer protective cover; and an inner thermal filler disposed between the outer protective cover and the central cooling tube and surrounding each of the optical fibers, wherein the central cooling tube, the outer protective cover, the inner thermal filler, and the plurality of optical fibers each extend along the length of the cable. Various systems and methods for removing defects from individual optical fibers and for distributing power over long distances using the optical fiber cable are also provided.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure generally relates to optical fibers, and more specifically to optical fiber cables, systems for distributing power using optical fiber cables or otherwise using these cables, and techniques for refining optical fibers included in such cables.

Background Art

[0002] Optical fiber cables can be used to transmit power to endpoints that are far from a power source. Typically, the term "power over fiber" means a system in which power generated by a power source is converted into optical power using a laser light source, this optical power is transmitted through an optical fiber cable to a photodetector, and the photodetector converts the optical power back into power and supplies it to an electrical load. As an example, a typical power over fiber system includes a laser diode, a multimode optical fiber formed of silica fiber, and a photovoltaic cell or other semiconductor device composed of a material such as gallium arsenide (GaAs), indium phosphide (InP), or indium gallium arsenide (InGaAs).

[0003] Power over fiber systems offer several advantages over typical power systems, including, for example, little or no risk of electrical interference, power outages due to lightning, and explosions ignited by electrical sparks. Also, optical fiber cables have a significantly higher power density, can withstand higher temperatures, and are much lighter than electrical cables. Furthermore, unlike electrical wires, the same optical fiber can be used to transmit optical power in one direction and, for example, return data in the other direction using different wavelengths or channels.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, conventional optical fiber power feeding systems using silica-based fibers are subject to transmission and distribution losses, conversion efficiencies on both the transmission side (i.e., conversion from electricity to light) and the reception side (i.e., conversion from light to electricity), and significant attenuation in the transmission medium itself, thus limiting the wide applicability of such systems. For example, high-power transmission over long distances (e.g., 800 kilometers (km) above ground or 50 km underwater) is achieved using high-voltage direct current (HVDC) power transmission systems that use copper or aluminum cables (also known as power or electrical superhighways) instead of silica-based fibers. Still, the conversion efficiency from alternating current (AC) to HVDC is considered to be as low as about 60%, and some existing undersea systems suffer total power losses of 65% or more.

[0005] Another known type of fiber is zirconium fluoride-barium fluoride-lanthanum fluoride-aluminum fluoride-sodium fluoride (ZrF4-BaF2-LaF3-AlF3-NaF), also known as "ZBLAN" fiber. ZBLAN is a type of fluoride glass that has better infrared transmittance and a significantly lower loss profile than standard silica. For example, as shown in FIG. 1, a standard silica fiber has a minimum loss of about 0.25 dB / km at 1550 nanometers (nm), whereas the theoretical loss limit of ZBLAN fiber is about 0.0001 dB / km, three orders of magnitude lower. However, in many cases, this loss limit is difficult to reach because ZBLAN often contains undesirable impurities or crystallites that can form during the manufacturing process and inhibit the transmission of the material.

[0006] Specifically, as shown in FIG. 2, ZBLAN has a temperature at which the ZBLAN fiber transitions from a solid glass to a liquid or viscous state (i.e., the glass transition temperature T g ) and a temperature at which crystallization occurs (crystallization temperature T x) The temperature difference with (...) is relatively small. Therefore, the operating range of ZBLAN is narrow, and thus crystallites are likely to form relatively easily during the drawing process. It has been shown that by growing ZBLAN under microgravity or micro-gravity (i.e., in space) rather than under unit gravity (i.e., on Earth), the crystallites can be suppressed or reduced due to the reduction of the convection process under microgravity conditions. However, the conventional techniques for manufacturing ZBLAN under microgravity conditions are extremely costly, time-consuming, and / or difficult to implement on a large scale because they require, for example, movement in space or the use of abandoned mine shafts on Earth.

[0007] Therefore, in this technical field, there is still a need for optical fiber cables and integrated optical fiber power supply systems that can efficiently transmit ultra-high power over long distances with significantly low losses.

[0008] The present invention aims to solve the above and other problems by a system, method, and apparatus configured to provide: (1) an optical fiber cable including a plurality of individual ZBLAN fibers capable of transmitting ultra-high output laser energy over long distances with significantly low losses; (2) a technique for removing defects from the optical fiber, including annealing the fiber within a micro-gravity environment formed on Earth; and (3) an optical fiber power supply system including the optical fiber cable, an ultra-high output laser light source coupled to a first end of the optical fiber cable, and a photodiode detector coupled to a second end of the optical fiber cable.

Means for Solving the Problems

[0009] One exemplary embodiment is a system for removing defects in a fixed-length optical fiber including a fiber core and a cladding surrounding the fiber core, the system comprising heating a given segment of the optical fiber to a temperature higher than the crystallization temperature (T x ) of the fiber and lower than the melting temperature (T mAn annealing unit including a heating chamber configured to heat internally to a first temperature lower than x ) and a heating chamber configured to move the annealing unit from a high place to a low place using free fall motion and further configured to maintain the first temperature of the segment of the optical fiber during the first period of free fall motion, the annealing unit, during a second period, cools the optical fiber segment at a critical cooling rate related to the optical fiber to a second temperature lower than the crystallization temperature (T g ) of the optical fiber and higher than the glass transition temperature (T

[0010] After the end of the second period, the annealing unit is further configured to move a subsequent segment of the optical fiber into the heating chamber, and the chamber is further configured to move the annealing unit from a low place to a high place, providing a system. x ) and lower than the melting temperature (T m ) of the fiber to a first temperature, (c) using one or more processors, moving the annealing unit from a high place to a low place using free fall motion, (d) during free fall motion, using the heating chamber and one or more processors to maintain a given segment at the first temperature for a first period, (e) during a second period, using one or more processors to cool a given segment of the fiber at a critical cooling rate related to the fiber to a second temperature lower than the crystallization temperature (T x ) of the fiber and lower than the glass transition temperature (T gCooling at the critical cooling rate of the fiber to a second temperature higher than

[0011] Yet another exemplary embodiment is a system for reducing defects in a length of optical fiber including a fiber core and a cladding surrounding the fiber core, the system comprising a heating element configured to selectively heat a given segment of the optical fiber to a first temperature higher than the crystallization temperature (T x ) of the fiber and lower than the melting temperature (T m ) of the fiber, a clamping system configured to selectively secure a given segment adjacent to the heating element, an annealing unit including the heating element and the clamping system, an acceleration chamber configured to move the annealing unit and a given segment of the optical fiber fixed within the annealing unit from a first position to a second position with a first acceleration and to move the annealing unit and the given segment from the second position to the first position with a second acceleration lower than the first acceleration, wherein the given segment of the optical fiber is heated by the heating element to the first temperature for a first period while at the first acceleration, the given segment is cooled for a second period at a second temperature lower than the crystallization temperature of the fiber and higher than the glass transition temperature (T g ) of the fiber at the critical cooling rate associated with the fiber, and the clamping system is configured to release a given segment of the optical fiber after the second period and secure a subsequent segment of the optical fiber adjacent to the heating element.

[0012] Another exemplary embodiment is a method for removing defects from a fixed-length optical fiber including a fiber core and a cladding surrounding the fiber core, at least partially disposed within an annealing unit of a system including one or more processors, the method comprising: (a) using one or more processors to fix a given segment of the optical fiber adjacent to a heating element of the annealing unit; and (b) using one or more processors and the heating element to heat the given segment to a first temperature higher than the crystallization temperature (T x ) of the fiber and lower than the melting temperature (T m ) of the fiber; (c) using one or more processors to move the annealing unit from a first position to a second position at a first acceleration; (d) while at the first acceleration, using one or more processors and the heating element to maintain the first temperature of the given segment for a first period; (e) during a second period, using one or more processors to cool the given segment at a critical cooling rate of the fiber to a second temperature lower than the crystallization temperature of the fiber and higher than the glass transition temperature (T g ) of the fiber; (f) after the second period, using one or more processors to release the given fiber segment; (g) using one or more processors to move the annealing unit from the second position to the first position at a second acceleration slower than the first acceleration; and (h) using one or more processors to repeat steps (a) through (g) for each subsequent segment of the optical fiber until the entire length of the optical fiber has been processed.

[0013] Yet another exemplary embodiment provides an optical fiber power supply system comprising a laser light source configured to emit high-power laser energy, a photodetector configured to convert detected light into electrical energy, and an optical fiber cable. The optical fiber cable includes a first end coupled to the laser light source, an opposite second end coupled to the photodetector, a length extending between the first end and the second end, and a plurality of optical fibers each extending along the length of the cable and having a thermal filler surrounding the fiber.

[0014] Another exemplary embodiment provides a method for managing power supply in an optical fiber power supply system comprising a transmitting unit having a laser light source, a receiving unit having a photodetector, and an optical fiber cable coupled between the transmitting unit and the receiving unit. The optical fiber cable includes a plurality of optical fibers each extending along the length of the cable. The method includes transmitting high-power laser energy from the transmitting unit to the receiving unit using a certain number of the optical fibers included in the optical fiber cable, receiving in a processor a data signal including information regarding power requirements of an electrical load coupled to the receiving unit and transmitted from the receiving unit to the transmitting unit using the optical fiber cable, and controlling the high-power laser energy output by the transmitting unit by adjusting, based on the power requirements of the electrical load, the number of optical fibers used to transmit the laser energy.

[0015] Yet another exemplary embodiment provides an optical fiber cable including a length extending between a first end and a second end, a central cooling tube, a plurality of optical fibers arranged radially around the cooling tube each including a fiber core and a cladding disposed around the fiber core, an outer protective cover, and an inner thermal filler disposed between the outer protective cover and the central cooling tube and surrounding each of the optical fibers, wherein the central cooling tube, the outer protective cover, the inner thermal filler, and the plurality of optical fibers each extend along the length of the cable.

[0016] As will be understood, the present disclosure is defined by the appended claims. This specification is a summary of aspects of the embodiments and should not be used to limit the claims. Other implementations are contemplated and are intended to be within the scope of this application in accordance with the techniques described herein, as will become apparent to those skilled in the art upon examination of the following drawings and detailed description.

[0017] To better understand the present invention, reference may be made to the embodiments shown in the following drawings. Components in the drawings are not necessarily to scale, and related elements may be omitted or, in some instances, the ratios may be exaggerated, so as to clearly show and emphasize the novel features described herein. Also, as is known in the art, system components can be arranged in various forms. Further, like reference numerals designate corresponding parts throughout the several views of the drawings.

Brief Description of the Drawings

[0018]

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[0019] The present invention can be embodied in various forms, but the present disclosure should be regarded as an exemplification of the present invention, and it is not intended to limit the present invention to the specific illustrated embodiments. With the understanding that the drawings show some exemplary and non-limiting embodiments, these will be described below.

[0020] In this application, the use of disjunctive words is intended to include conjunctive words. The use of definite and indefinite articles is not intended to indicate the cardinality of elements. Specifically, references to an object preceded by "the" (English definite article) or "a" and "an" (English indefinite articles) are intended to indicate one of the possible plurality of such objects.

[0021] In the following description, elements, circuits, and functions may be shown in block diagram form in order not to obscure the present disclosure with unnecessary details. Also, the block designations and the partitioning of logic between various blocks are examples of particular embodiments. Further, those skilled in the art will understand that the information and signals shown in the block diagrams can be represented using a variety of different one or more technologies. For example, although a figure may represent data, instructions, signals, or commands, it will be understood that these may also represent voltage, current, electromagnetic waves, magnetic fields, or optical fields, or combinations thereof. Also, in some of the drawings, a signal is represented as one signal for clarity of explanation, but those skilled in the art will recognize that this signal may also represent a bus of multiple signals. The various exemplary logical blocks, modules, and circuits described in connection with the embodiments disclosed herein can be implemented or executed using one or more processors. As will be well understood by those skilled in the art, the disclosure of separate processors in the block diagrams can represent multiple processors that execute the functions or logical sequences disclosed herein, or can represent multiple functions or sequences executed on a single processor.

[0022] The systems, methods, and apparatuses described herein provide a technique for improving ZBLAN fibers and provide an optical fiber cable composed of a plurality of strands of modified ZBLAN fibers that can transmit a large amount of power over a very long distance with significantly low loss. Also provided is an optical fiber power supply system that uses an optical fiber cable as a transmission medium between a light source included in an electro-optical conversion unit and a photodetector included in an opto-electrical conversion unit.

[0023] The uses of the optical fiber power feeding system are envisioned to be various, including optical power distribution systems and medical or surgical applications. Embodiments include an optical power distribution system that uses an optical fiber cable as an interconnector for transmitting ultra-high-capacity (e.g., sufficient to power a small country) optical power between continents under submarine or subsea conditions. For example, the optical power distribution system can distribute up to 1 gigawatt of power over a distance of about 1000 km at sea level or about 50 km underwater. Other embodiments provide an optical power distribution system that uses an optical fiber cable to distribute power between substations via a power distribution network and / or to power relay towers in residential and commercial environments in power over ethernet (POE) applications and / or to distribute power in various automotive and aerospace applications.

[0024] FIG. 3 shows an exemplary optical fiber power feeding system 100 according to an embodiment, including a light source 102, an optical fiber cable 104, and a photodetector 106. As shown, the optical fiber cable 104 includes a first end 108 coupled to the light source 102, an opposite second end 110 coupled to the photodetector 106, and a length x extending between the first end and the second end. In an embodiment, each of the light source 102, the optical fiber cable 104, and the photodetector 106 can be optimally configured to maximize the conversion efficiency, maximize the power transmission distance, and minimize the insertion loss. The optical fiber power feeding system 100 can be used in various applications that require the transmission of optical power between two points, such as, for example, a power distribution system for commercial, residential, or other applications (e.g., as shown in FIG. 13) and a surgical device (e.g., as shown in FIG. 15).

[0025] The light source 102 includes one or more laser diodes or other semiconductor devices that can convert electrical energy into light energy and emit light energy. In some embodiments, the light source 102 is part of a large-scale electrical-optical conversion unit as shown, for example, in FIG. 12. In a preferred embodiment, the light source 102 is a high-efficiency laser light source that can emit ultra-high output laser energy with an ultra-low threshold current. As an example, the light source 102 (also referred to herein as a "laser light source") can include one or more high-power laser diode bars (e.g., GaInAsSb / AlGaAsSb diodes) operating at a wavelength of about 2.1 micrometers (μm). As another example, the laser diode within the light source 102 can be a multi-emitter multi-mode laser diode or any other suitable laser diode having a wavelength of about 980 nanometers (nm) and an output power of about 420 watts (W). In one embodiment, the light source 102 has a conversion efficiency of at least about 85 percent and a peak power delivery per link of at least about 1 gigawatt (GW). In some embodiments, the light source 702 includes a plurality of laser diodes (e.g., a diode array) arranged in an array. In such cases, each diode can be individually controlled (e.g., turned on or off) to change or control the total output power of the light source 102. The light source 102 can further include one or more monitor diodes configured to stabilize the output of the light source 102 (e.g., prevent fluctuations in laser energy). In some embodiments, the monitor diodes of the light source 102 are further configured to monitor signals (e.g., optical data signals) received from the photodetector 106 in the light source 102 and supply these signals to a processor (e.g., the processor 730 of FIG. 7).

[0026] The photodetector 106 includes a photodiode, a photovoltaic cell, or other semiconductor device that can detect laser light or other light energy and convert the detected light into electrical energy. In some embodiments, the photodetector 106 is part of a large-scale optical-to-electrical conversion unit, such as shown in FIG. 12 for example. In a preferred embodiment, the photodetector 106 includes one or more high-efficiency photodiode detectors (e.g., 4-junction InGaAs). In one embodiment, the photodetector 106 has a conversion efficiency of at least about 85 percent and a peak power supply per link of at least about 1 gigawatt (GW), and has a continuous power transmission of about 1 watt (W).

[0027] The optical fiber cable 104 can serve as a transmission medium for carrying optical power from the light source 102 to the photodetector 106. The optical fiber cable 104 can also be configured to transmit data signals in addition to optical power, as shown in FIG. 13 for example. In a preferred embodiment, the optical fiber cable 104 is a super high-power cable that includes a plurality of optical fibers bundled together, having a cooled central portion and a thermal acrylic filler surrounding each optical fiber extending along the length of the cable and including ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN). In one embodiment, the optical fiber cable 104 can transmit laser energy having a power of at least about 1 gigawatt (GW) over a distance of at least about 1000 kilometers (km) with a loss of about 0.1 decibel (dB) and a power density of 0.4 GW / cm 2 and can transmit it over a distance of at least about 1000 kilometers (km).

[0028] FIG. 4 shows a cross-sectional view of an exemplary optical fiber cable 200 according to an embodiment. The optical fiber cable 200 can be included as the optical fiber cable 104 in the optical fiber power supply system 100 or in any of the other systems described herein. In other embodiments, the optical fiber cable 200 can be configured to transmit communication signals over long distances instead of optical power.

[0029] As shown in the figure, the optical fiber cable 200 includes a plurality of optical fibers 202 arranged radially around the central cooling tube 204 and wrapped by an outer protective cover 206. According to some embodiments, the optical fiber cable 200 can include any number of fibers 202 selected from a range of about 5 to 10 fibers depending on the desired power capacity and transmission distance. In one such embodiment, the optical fiber cable 200 includes a bundle of eight optical fibers 202 and transmits laser energy having at least about 1 gigawatt (GW) of power over a distance of at least about 1000 kilometers (km) with a loss of about 0.1 decibel (dB) and a power density of 0.4 GW / cm 2 The power density can be transmitted. In other embodiments, the optical fiber cable 200 includes up to about 8000 optical fibers 202 to accommodate ultra-high-capacity power transmission needs.

[0030] By bundling a plurality of fibers 202 into one optical fiber cable 200, the cable 200 can be used to change the power distribution to an endpoint or an electrical load coupled thereto by simply controlling the number of fibers 202 used for power transmission. In this way, the transmitted optical power can be temporarily matched to the distribution needs of the electrical load.

[0031] The cooling tube 204 is configured to increase the power capacity of the cable 200 by neutralizing or dissipating the heat generated by the optical fibers 202 during power transmission. For example, the cooling tube 204 can be configured to keep the temperature of the cable 200 below the thermal expansion temperature of the ZBLAN fiber and well below the glass transition temperature of ZBLAN (e.g., about 315 degrees Celsius (°C)). In one example embodiment, the cooling tube 204 is configured to maintain or keep the overall temperature of the cable 200 below 100 °C. In other embodiments, the cooling tube 204 can be configured to maintain the cable temperature at or below a different threshold temperature.

[0032] According to an embodiment, the cooling tube 204 includes a hollow interior filled with a suitable cooling substance or coolant 208, such as, for example, air or other gas, or a suitable oil or other liquid. For example, the coolant 208 can include a mineral oil or alkylate such as linear decylbenzene or branched nonylbenzene. In some embodiments, the two ends of the cooling tube 204 (e.g., at both ends of the cable 200) can be kept open so that the coolant 208 is cold air and the cold air can passively spread through the tube 204. In other embodiments, the coolant 208 is cold air or a liquid that is actively pushed through the entire tube 204 using a coolant management pump (not shown) disposed at one or more ends of the cable 200 (e.g., within a connector). In addition to having cooling properties, the substance 208 can also be configured to maintain the mechanical integrity of the tube 204 by maintaining a threshold amount of pressure within the cooling tube 204. The exact amount of pressure required can vary depending on the number of fibers 202 included in the cable 200, the type of coolant 208, and the operating environment of the cable 200 (e.g., underwater or underground).

[0033] The cooling tube 204 itself can be formed of aluminum, acrylic, or other suitable materials. For example, if a thicker wall and / or higher mechanical stability is required (e.g., when the cable 200 includes a large number of fibers 202 and thus transmits a large amount of power and generates a large amount of heat), the cooling tube 204 can be formed of aluminum. As another example, if a thinner wall is sufficient (e.g., when the cable 200 includes a small number of fibers 202 and thus transmits less power and generates less heat), the cooling tube 204 can be formed of acrylic. In embodiments where the cable 200 transmits a small amount of power, the diameter of the cooling tube 204 can be made very small or the cooling tube 204 can be completely eliminated.

[0034] (Also referred to as a "protective jacket"), the outer protective cover 206 is made of polyurethane (PUR) or polyvinyl chloride (PVC) and is configured to protect and isolate the fiber 202 and the cooling tube 204 from external physical forces and chemical degradation. The protective cover 206 also provides a housing that encloses the internal components of the cable 200. In some embodiments, the outer protective cover 206 includes a plurality of material layers that are concentrically arranged and joined to each other to form the cover 206.

[0035] As shown in FIG. 4, the optical fiber cable 200 further includes an inner thermal filler 210 that is disposed between the outer protective cover 206 and the central cooling tube 204 and surrounds each of the optical fibers 202. In an embodiment, the thermal filler 210 is configured to maintain the spatial or mechanical integrity of the cable 200 and to maintain a consistent temperature throughout the cable 200. For example, the thermal filler 210 isolates between the individual fibers 202 by completely surrounding each of the optical fibers 202, or prevents contact therebetween, thereby avoiding the formation of hot spots when there is heat accumulation in one or more of the fibers 202. Further, the thermal filler 210 can have a porous structure composed of a plurality of different sized holes to provide variable thermal insulation and structural integrity. When air flow passes through these holes, heat is transmitted or transferred throughout the filler 210, thus suppressing or preventing heat from accumulating around a particular fiber 202. According to an embodiment, the thermal filler 210 can be composed of acrylic (e.g., polymethyl methacrylate (PMMA)) or other suitable materials.

[0036] The optical fiber cable 200 has a length (e.g., the length x shown in FIG. 3) that extends between a first end and a second end, and each of the central cooling tube 204, the outer protective cover 206, the inner thermal filler 210, and the plurality of optical fibers 202 extends along the length of this cable 200. Accordingly, each of the optical fibers 202 can extend substantially parallel to the central cooling tube 204, and the outer protective cover 206 can be concentrically aligned with the cooling tube 204.

[0037] According to an embodiment, each optical fiber 202 is a multimode fiber having a fiber core 212 and a cladding 214 disposed around the fiber core 212. The fiber core 212 can be disposed at the center of the cladding 214 and fused or joined to the cladding 214. The core 212 includes a ZBLAN fiber drawn in a microgravity environment and can be a step index fiber core having a diameter selected to optimize power transmission along the length of the fiber 202. In some embodiments, the fiber core 212 has a diameter selected from the range of about 200 μm to about 400 μm. In other embodiments, the fiber core 212 has a diameter selected from the range of about 300 μm to about 500 μm. In one example embodiment, the core diameter is about 600 μm.

[0038] The cladding 214 can be configured to confine light within the fiber core 212 by causing total internal reflection at the boundary between the cladding 214 and the core 212. In an embodiment, the cladding 214 can be formed of a fluoride glass material that is similar to the ZBLAN fiber material but optically different. For example, the cladding 214 can be composed of a material having a refractive index lower than that of the fiber core 212. The thickness of the cladding 214 can be selected based on the core diameter, the desired overall diameter for the optical fiber 202, the optimal ratio between these two values that minimizes the thickness of the cladding 214 without impairing light transmission through the fiber 202, and / or the desired amount of flexibility for the entire fiber 202. As an example, in an embodiment where the fiber core 212 has a diameter of about 400 μm, the cladding 214 (and thus the entire fiber 202) can have a diameter of about 460 μm. Also, in embodiments where the core diameter is small, the cladding diameter can be proportionally smaller.

[0039] The overall diameter of the optical fiber cable 200 or the diameter of the outer protective cover 206 can depend on the diameter of each individual fiber 202, the number of fibers 202 included in the cable 200, the diameter of the cooling tube 204 and the thermal filler 210, and / or the thickness of the outer protective cover 206. As an example, in the illustrated embodiment, the optical fiber cable 200 includes a bundle of eight ZBLAN optical fibers 202 each having a diameter of about 500 microns and an outer protective cover 206 having a diameter of about 5 millimeters (mm).

[0040] The ZBLAN optical fibers 202 are improved or modified prior to the manufacture of the optical fiber cable 200 using one or more annealing methods such as, for example, the method 300 shown in FIG. 6 and / or the method 500 shown in FIG. 8. These methods are configured to optimize the fibers 202 for longer transmission by removing or reducing defects that cause scattering losses within the core and cladding of the ZBLAN. Further, conventional methods for improving a significant amount of ZBLAN fiber require movement into space (e.g., within a LEO satellite or the International Space Station) to obtain the necessary low-gravity or zero-gravity environment, whereas the annealing methods described herein can be achieved without leaving the Earth or using an aircraft.

[0041] Generally, these methods involve processing off-the-shelf ZBLAN fibers, such as the optical fiber 202 shown in FIG. 4, in very short segments to remove crystals and other defects within the fiber, and thus improve the off-the-shelf fiber. According to an embodiment, this process involves heating the fiber to a temperature well above the glass transition temperature (T g ) of the ZBLAN and above the crystallization temperature (T x ) but lower than the melting temperature (T m ). For example, in an embodiment where the ZBLAN fiber has a T g of about 260 degrees Celsius (°C), a T x of about 352 °C, and a T m of about 450 °C, the ZBLAN fiber is annealed at a temperature of about 370 °C (T a) can be heated. The process involves heating the ZBLAN fiber at the annealing temperature while accelerating it at the acceleration due to the Earth's gravitational acceleration (e.g., 9.8 meters per second per second (m / s 2 )) for a predetermined time to mimic a free-fall environment or a micro-gravity environment. Next, the process includes rapidly cooling or quenching the fiber to a quench temperature (T q ) that is below the crystallization temperature. In some embodiments, the quench temperature is about 10 - 20 °C below the annealing temperature. For example, in an embodiment where the annealing temperature is about 370 °C, the quench temperature can be about 350 °C. To help avoid introducing new crystallites during this process, the cooling step is initiated while the fiber is still in a free-falling state, thus ensuring that the annealing step is completed before gravity becomes present.

[0042] The process of making a complete ZBLAN fiber can be monitored in-situ using a combination of a laser and a photodetector, or other devices that can measure in real-time the amount of incident light scattered by the scattering profile of the fiber or defects within the material. The scattering profile indicates the proportion of crystallites in the ZBLAN fiber and can thus be used to determine the effectiveness of the annealing process. If the real-time monitoring results indicate a high proportion of crystallites, the process can be repeated through multiple cycles until an optimal fiber loss metric is achieved.

[0043] FIG. 5 shows an exemplary acceleration profile 250 of a ZBLAN fiber during the process described herein, according to an embodiment. As shown, the acceleration profile 250 changes over three periods. During the first period t1, the fiber accelerates from zero acceleration (a = 0) to the standard free-fall acceleration or gravity (g 2 ) equal to about 9.8 m / s o ). Also, during this first period, the fiber is heated from the starting temperature to the annealing temperature T aIt is heated to (for example, 370 °C). This first period t1 can also be called a "ramp up" period. During the second period t2, the fiber continues to move under the acceleration of gravity. Also, during the second period, the fiber continues to be heated to the annealing temperature or is held at the annealing temperature for a predetermined length of time. During the third period t3, the fiber decelerates and returns to a stationary state. Also, during the third period, the fiber is cooled to the quenching temperature T q in a preset length of time.

[0044] In an embodiment, the second period t2 includes a first predetermined length of time for heating the fiber and a second predetermined length of time for cooling the fiber. Since the first length of time includes the period during which the fiber is annealed or heated to the annealing temperature, it can be considered as the annealing period of the fiber. The second length of time forms part of the cooling period of the fiber. This cooling period also includes at least a part of the third period t3, that is, at least a part of the preset length of time required to cool the fiber to the quenching temperature. According to an embodiment, the second length of time is located at the end of the second period t2 such that the cooling period starts during the acceleration. This ensures that the fiber is still in a free-falling state when the fiber temperature drops below the annealing temperature, thus preventing new crystallites from being formed while the fiber is cooling. In various embodiments, the first length of time is longer than the second length of time. In some embodiments, the length of the annealing period and the length of the cooling period are substantially equal.

[0045] The exact duration of each of the three periods (t1, t2, and t3) can be determined based on a plurality of factors. For example, the first period can depend on the acceleration rate of the fiber and the heating rate of the elements used for heating the fiber. The second period can depend on, in addition to the acceleration due to free fall, the distance the fiber travels during acceleration (e.g., descent by free fall), and the length of the fiber to be annealed. The third period can depend on the critical cooling rate (CCR) associated with the ZBLAN fiber and the deceleration rate of the fiber. As an example, in some embodiments, the ZBLAN fiber has a critical cooling rate of 40 °C / s. In such a case, for a fiber length of about 1 meter, a second period of about 320 milliseconds (ms) is considered necessary, and the first and third periods are much shorter (e.g., 100 ms). FIG. 5 shows the periods t1 and t3 to be approximately equal, but in other cases, these two periods can vary or be different from each other, for example, depending on the factors described above.

[0046] In some embodiments, the acceleration rate or speed at which the fiber accelerates during the first period can be determined based on some characteristics of the ZBLAN fiber, such as the scattering and absorption levels of the fiber length at a given wavelength (e.g., 650 nanometers (nm)), and the mechanism (e.g., actuator) used to put the fiber in a free - fall state or otherwise release the fiber within a gravitational field. Similarly, the deceleration rate or speed at which the fiber decelerates during the second period can be determined based on the same fiber characteristics and the mechanism (e.g., gripper or brake) used to add frictional force to decelerate the movement of the fiber.

[0047] FIG. 6 shows a first exemplary process or method 300 for removing defects from a length of optical fiber that includes a fiber core and a cladding surrounding the fiber core. In embodiments, the optical fiber can be the same as or substantially similar to the optical fiber 202 shown in FIG. 4. FIG. 7A shows an exemplary fiber refining system 400 configured to remove defects from a length of ZBLAN fiber. In some embodiments, the system 400 can be used to perform the process 300. Accordingly, in the following paragraphs, the process 300 will be described in connection with the system 400 for ease of explanation. However, it should be understood that in other embodiments, the process 300 can also be performed using other systems or devices capable of annealing ZBLAN fiber.

[0048] Referring initially to FIG. 7A, according to an embodiment, a fiber improvement system 400 includes a chamber or tower 402 (also referred to as a "drop tower"), and one or more annealing units 404 movably disposed within the tower 402 and configured to process a given segment of an optical fiber 406. The tower 402 can be configured to mimic a microgravity environment by placing each annealing unit 404 in a free-fall state for a predetermined time (e.g., the second period shown in FIG. 5). In one example embodiment, the tower 402 is about 44 meters in height and is configured to provide at least a 3-second free-fall state to process a segment of the optical fiber 406 that is about 10 meters in length. FIG. 7A shows the tower 402 including annealing units 404a and 404b, but it should be understood that in other embodiments, the tower 402 can include only one or more than two annealing units 404. In an embodiment, the fiber improvement system 400 further includes one or more processors configured to communicate with the tower 402, one or more annealing units 404, and / or various other components of the system 400 and execute process 300 to improve the optical fiber 406 according to the techniques described herein, or otherwise control the components of the system 400.

[0049] FIG. 7B shows an exemplary annealing unit 404 according to an embodiment. As shown, the optical fiber 406 is disposed within the annealing unit 404 and configured to undergo free fall or gravitational acceleration when the unit 404 is dropped or released within the tower 402. The optical fiber 406 includes a ZBLAN fiber core and a cladding disposed around the fiber core and can be substantially similar or identical to the optical fiber 202 shown in FIG. 4. FIG. 7B shows the optical fiber 406 fully contained within the annealing unit 404, but in other embodiments, the annealing unit can be configured such that a portion of the optical fiber is contained within and the remaining portion is disposed outside of the annealing unit.

[0050] Referring again to FIG. 7A, tower 402 is coupled to one or more annealing units 404 and further includes a movable component 407 configured to move each annealing unit 404 from a high position to a low position in free fall motion, as shown, for example, by annealing unit 404a. The movable component 407 can be further configured to return the annealing unit 404 from a low position to a high position, as shown, for example, by annealing unit 404b. According to an embodiment, the distance h between the high position and the low position is selected to ensure that the free fall motion continues long enough to cause at least one improvement of a ZBLAN fiber of a given length or to complete at least one cycle of the annealing and cooling processes described herein (e.g., method 300 shown in FIG. 6). In some embodiments, the distance h is selected to allow completion of multiple annealing cycles within a single fall. The time (in milliseconds) required for the free fall period (e.g., the second period t2) in each cycle, as well as the lengths of the acceleration (or startup) and deceleration periods (e.g., the first and third periods t1 and t3), can be calculated using the acceleration profile 250 shown in FIG. 5. The acceleration profile 250 can also determine the length of fiber that can be processed within one cycle. In one exemplary embodiment, the distance h is about 44 meters (m), the annealing unit 404 takes about 3 seconds to travel this distance, and the annealing unit 404 is configured to process about 10 meters of fiber within this time (e.g., 10 m / cycle).

[0051] In some embodiments, the movable component 407 includes a pulley system comprising one or more pulleys 408 and one or more cables 410 slidably coupled to the pulley(s) 408. Each cable 410 can be slidably coupled to at least one annealing unit 404, and the pulley system 407 can be configured to convey and support the unit 404 as it moves the unit 404 from a high position to a low position and then back to a high position.

[0052] For example, in the illustrated embodiment, the pulley system 407 includes a first pulley 408a disposed at or adjacent to a high location and a second pulley 408b disposed at or adjacent to a low location. As shown, the cable 410 can form a loop around the pulleys 408a and 408b. The pulleys 408a and 408b can be configured to rotate in two directions: a first direction to move the annealing unit 404 from a high location to a low location and a second direction to return the annealing unit 404 from the low location to the high location. The pulley system 407 can be configured to place the unit 404 in a free-fall state when the annealing unit 404 slides downward along the cable 410 towards the low location. For example, the cable 410 can be configured to impart zero or minimal frictional force to the annealing unit 404 when the unit 404 moves towards the low location. Upon reaching the low location, both pulleys 408a and 408b rotate in the second direction to pull back the cable 410 and the annealing unit 404 attached to the cable 410 to the high location along the same path.

[0053] In other embodiments, the pulley system 407 can include a plurality of independent pulley systems each coupled to a separate annealing unit 404. In such cases, these annealing units 404 can be dropped individually from a high location to a low location on separate cables and pulled back to the high location individually using separate pulleys. For the movable component 407, other configurations are also envisioned, including, for example, a lift system configured to drop the annealing unit onto a platform disposed at a high location and lift the platform and the annealing unit back to the high location.

[0054] In an embodiment, the tower 402 further includes a brake system 411 configured to be coupled to the movable component 407 to control the movement of the movable component 407 and / or the movement of the annealing unit 404 coupled to the movable component 407. For example, in the illustrated embodiment, the brake system 411 can be coupled to one or more of the pulley 408 and / or the cable 410, and configured to stop the rotation of the (single or multiple) pulley 408 in a first direction, or otherwise prevent the movement of the cable 410 between the first pulley 408a and the second pulley 408b, so as to stop the free-fall acceleration of the annealing unit 404. As an example, the brake system 411 can include one or more brakes (not shown) coupled to the cable 410 and / or one or two or more pulleys 408, and can be configured to activate these brakes when a stop operation is desired. In some cases, the brake system 411 can be used to stop the annealing unit 404 at a lower position when it is moving in a first direction, and also stop the annealing unit 404 at a higher position when it is moving in a second direction. In some embodiments, the brake system 411 is further configured to start the free-fall movement of the annealing unit 404 by releasing the brake so that the pulley 408 rotates in the first direction and / or the cable 410 freely moves otherwise towards the lower position.

[0055] As shown in FIG. 7B, each annealing unit 404 includes a heating chamber 412 that heats the optical fiber 406, or specifically, a given segment 406a of the optical fiber 406 disposed within the chamber 412. The annealing unit 404 further includes one or more components that feed incremental portions of the optical fiber 406 through the heating chamber 412. Specifically, the annealing unit 404 includes a first spool 414 configured to hold or store the length of the unmodified or pre-annealed optical fiber 406 and supply the unmodified optical fiber 406 into the heating chamber 412. The annealing unit 404 also includes a second spool 416 configured to receive and store the length of the modified or annealed optical fiber 406 that includes the modified segment of the optical fiber 406 exiting the heating chamber 412. Thus, initially the entire length of the optical fiber 406 can be stored on the first spool 414 and gradually transferred to the second spool 416 as more and more of the optical fiber 406 is processed by the system 400. The annealing unit 404 can also include one or more pulleys or reels that help guide the optical fiber 406 between the first spool 414, the heating chamber 412, and the second spool 416. According to an embodiment, each segment 406a received in the heating chamber 412 can have a substantially uniform length, such as, for example, about 10 meters (m). The exact length of the segment 406a can depend on the distance available for free fall (e.g., the distance h in FIG. 7A) and / or the physical constraints of the annealing unit 404.

[0056] According to an embodiment, the heating chamber 412, as part of a process to remove defects from the optical fiber 406, subjects a given segment 406a of the optical fiber 406 to a temperature that is higher than the crystallization temperature (T x ) of the fiber core and much higher than the glass transition temperature (T g ) of the fiber core but lower than the melting temperature (T m) It is configured to heat to a first temperature lower than ). Thus, the first temperature can be high enough to remove the crystals in the fiber core and cladding but low enough to avoid completely melting the glass. In an embodiment, the ZBLAN fiber has a glass transition temperature of about 260 °C, a crystallization temperature of about 352 °C, and a melting temperature of about 450 °C. Accordingly, the first temperature can be any value between 352 °C and 450 °C. In one embodiment, the first temperature is about 370 °C.

[0057] As described herein, segment 406a remains at the first temperature while annealing unit 404 is in a free-fall state. For example, heating chamber 412 can be configured to heat a given segment 406a to the first temperature immediately before annealing unit 404 starts a free-fall motion, and continue to heat the given segment 406a during this free-fall motion to keep the first segment 406a at the first temperature for a predetermined time (i.e., the annealing period). According to an embodiment, the predetermined time can depend on the length of segment 406a and other factors described herein.

[0058] In an embodiment, heating chamber 412 includes a heating coil or any other suitable heating element that can be accurately controlled to a specific temperature. For example, heating chamber 412 can include a ceramic or metal heating element that can be set to a desired temperature using an input value. In one example embodiment, the heating element has a specific heat capacity of about 0.888 J / g·°C that ensures a sufficiently rapid change in the temperature of the heating element.

[0059] In some embodiments, heating chamber 412 further includes a thermocouple or other device that monitors the real-time temperature of the heating element and adjusts its output temperature to the heating element as needed. For example, the thermocouple can be electrically connected to the heating element to increase or decrease its output temperature according to how the real-time temperature reading compares to the desired temperature value.

[0060] In some embodiments, the heating chamber 412 further includes an independent processor that controls the operation of these heating elements and thermocouples. In other embodiments, the heating chamber 412 is electrically coupled to the processor 418 of the annealing unit 404, and the processor 418 is configured to manage the heating function of the heating chamber 412. In still other embodiments, the heating chamber 412 can be electrically coupled to one or more other processors of the system 400 that perform the operations described herein.

[0061] As the next step in the defect removal process, the annealing unit 404 can be further configured to rapidly cool or quench the heated segment 406a to a second temperature that is lower than the crystallization temperature (T x ) but higher than the glass transition temperature (T g ). In one example embodiment, the second temperature is about 350 °C, or about 10 °C to 20 °C lower than the first temperature. Also, the annealing unit 404 can be configured to cool the heated segment 406a at a critical cooling rate associated with the optical fiber that determines how long the cooling process takes (i.e., the cooling period). In an embodiment, the critical cooling rate of the ZBLAN fiber is 40 °C / s. In such a case, it takes about 2 seconds to cool a fiber segment 406a that is about 10 meters in length.

[0062] In some embodiments, the fiber segment 406a can be cooled as it exits the heating chamber 412. For example, the second spool 416 can be configured to draw a given segment 406a of the optical fiber 406 from the heating chamber 412 at a rate or speed selected based on the critical cooling rate and the ambient temperature of the annealing unit 404 such that the heated segment 406a cools to a second temperature when it reaches the second spool 416. In other embodiments, a given fiber segment 406a can be cooled to a second temperature within the heating chamber 412. For example, the temperature of the heating chamber 412 can be rapidly decreased to the second temperature to quench the heated segment 406a. In such cases, the heating element can be decreased to the second temperature, for example, by reducing or removing the amount of current applied to the heating element.

[0063] As shown in FIG. 7B, the annealing unit 404 further includes one or more processors 418 (also referred to herein as "processor 418") configured to control one or more functions of the annealing unit 404, for example, according to the process 300 of FIG. 6. In other embodiments, the one or more processors 418 can be included in another component of the system 400 and configured to communicate with the annealing unit 404 and / or components included in the annealing unit 404 to control the operation of the annealing unit 404.

[0064] In some embodiments, the processor 418 is electrically coupled to the heating chamber 412 to control the temperature setting of the heating element within the chamber 412. For example, the processor 418 can increase the temperature setting to a first temperature during annealing. The processor 418 can also be configured to increase or decrease the temperature setting based on a temperature reading received from a sensor (e.g., a thermocouple) disposed within or on the heating chamber 412.

[0065] In some embodiments, processor 418 is electrically coupled to the first and second spools 414 and 416 to control the movement of the spools, including their rotational speed and direction. For example, processor 418 can be configured to rotate the second spool 416 in a first direction to pull a given segment 406a out of chamber 412 and draw a subsequent segment 406b of the optical fiber 406 into chamber 412. Processor 418 can also be configured to rotate the first spool 414 in a second direction opposite the first direction to reverse the direction of movement of the optical fiber 406, for example when a given segment 406a has to be returned to the heating chamber 412 for further processing.

[0066] In addition, processor 418 can be configured to control the speed at which the first and / or second spools 414 and 416 rotate, and thus the speed or rate at which the optical fiber 406 enters and exits the heating chamber 412. In some embodiments, the rotational speed of the second spool 416 is selected such that when the heated segment 406a exits the chamber 412, the segment 406a rapidly cools to a second temperature at a critical cooling rate associated with the optical fiber. For example, if the heated segment 406a has a length of 1 meter and the spool size or circumference of the spool is also approximately 1 meter, the spools 414, 416 can be configured to rotate at a speed or rate of one rotation per second to supply the heating chamber 412 with 1 meter of fiber (or one fiber segment 406a) per second. In such embodiments, the annealing unit 404 can be configured to process 1 meter of fiber per second. As will be appreciated, the rotational speed can be adjusted as needed to accommodate segments of larger (e.g., 10 meter long) fibers.

[0067] In various embodiments, annealing unit 404 performs post-annealing analysis of a given segment 406a to determine whether further processing is needed to obtain optimal results. Specifically, annealing unit 404 further includes one or more lasers or other sensors that monitor or measure the scattering profile of segment 406a after completion of the cooling step. The measurement information can be provided to processor 418 for real-time analysis. Processor 418 can be configured to determine the fiber loss value of annealed segment 406a based on the measurement information and compare this measured value with a fiber loss threshold stored in memory. If the threshold is not met, processor 418 can be configured to return segment 406a to heating chamber 412 for further processing, for example, by rotating second spool 416 in a second direction (e.g., clockwise) to move a given segment 406a in the reverse direction.

[0068] Specifically, a laser (e.g., a 632 nanometer (nm) laser) can be configured to direct light towards fiber segment 406a either after the fiber segment 406a exits heating chamber 412 or while it is present inside chamber 412, depending on where the cooling process takes place. The laser can be appropriately positioned within heating chamber 412 or at another location within annealing unit 404. Annealing unit 404 can also include a photodetector that is arranged opposite the laser such that fiber segment 406a passes between the laser and the photodetector or crosses a line of sight established between these two devices. The photodetector can be configured to receive the light that has passed through fiber segment 406a and generate an output (e.g., a current value) representative of the detected laser power or amount of laser light. For example, the photodetector can be configured to measure the amount of red light (e.g., 650 nm) that is not scattered by the crystal or that can pass straight through the fiber glass.

[0069] Processor 418 can be electrically coupled to the photodetector and configured to compare the photodetector output with a threshold or predicted current level. If the measured quantity is too low, processor 418 can return fiber segment 406a into heating chamber 412 for reprocessing. In some embodiments, the annealing and cooling processes can be repeated until an optimum scattering coefficient or other fiber loss metric (e.g., 0.1 decibel per kilometer (dB / km) at 650 nm) for a given optical wavelength is achieved.

[0070] Next, referring again to FIG. 6, process 300 will be described with reference to the components of system 400. In an embodiment, process 300 can be implemented using one or more processors of system 400, including, for example, processor 418. As shown, process 300 begins at block 302 by placing or positioning a given segment of an optical fiber (e.g., fiber segment 406a) within a heating chamber (e.g., heating chamber 412) of an annealing unit (e.g., annealing unit 404) for processing or refinement. The fiber segment can be moved into the heating chamber by rotating a spool (e.g., spool 414) that holds the fiber prior to annealing in a first direction towards the heating chamber. At block 304, the fiber segment is heated to a first temperature that is higher than the crystallization temperature (T x ) of the optical fiber but lower than the melting temperature (T m ) of the fiber. For example, the first temperature can be about 370 °C, or any other value between 352 °C and 450 °C.

[0071] At block 306, the fiber segment within the annealing unit is subjected to the acceleration of gravity on Earth (e.g., 9.8 m / s 2) To accelerate, the annealing unit is dropped or moved from a high position to a low position using free fall motion. The free fall motion can be achieved by controlling the movement of a movable component (e.g., pulley system 407) coupled to the annealing unit. Also, the movable component can be configured to maintain the free fall motion for a minimum time (e.g., 3 seconds). In block 308, the temperature of the fiber segment is maintained at a first temperature over a first period during this free fall motion. (In this specification, this first period is also referred to as the "annealing period".)

[0072] In block 310, the fiber segment is cooled to a second temperature over a second period (also referred to as the "cooling period" in this specification). The second temperature can be a temperature that is below the crystallization temperature (T x ) but above the glass transition temperature (T g ). In one example embodiment, the second temperature is about 350 °C, or about 10 °C - 20 °C lower than the first temperature. When the second period ends, the first processing cycle can be considered complete.

[0073] According to an embodiment, the second period can start while the fiber segment is in free fall motion and end after the free fall motion stops or while the fiber segment is decelerating (e.g., within the third period t3 in FIG. 5). Thus, the time allocated to free fall can be spent on heating and at least partially cooling the fiber segment. In some embodiments, the first period is substantially equal to the second period. In other embodiments, the second period can be longer than the first period. As will be understood, the exact length of the first period can be determined based on the physical length of the fiber segment and other factors described in this specification.

[0074] In block 312, a movable component is used to move the annealing unit from a lower position to a higher position. In block 314, one or more processors of the annealing unit (e.g., processor 418) determine whether the processed fiber segment meets the fiber loss threshold stored in the unit's memory. If the determination in block 314 is "no" (i.e., the threshold is not met), process 300 returns to block 304 and begins processing the fiber segment again (i.e., repeats blocks 304 - 314). If the determination in block 314 is "yes" (i.e., the threshold is met or exceeded), process 300 proceeds to block 316.

[0075] In block 316, one or more processors determine whether there is a subsequent fiber segment remaining in the fiber pool before annealing (e.g., the first spool 414). If the determination in block 316 is "no", process 300 ends. If the determination in block 316 is "yes", process 300 returns to block 302 and begins processing the next fiber segment. Thus, process 300 can repeat any number of times until the entire length of the fiber before annealing is sufficiently improved or the target fiber loss threshold (e.g., less than 0.1 dB / km at 650 nm) is met.

[0076] FIG. 8 shows a second exemplary method or process 500 for removing defects from a length of optical fiber that includes a fiber core and a surrounding cladding according to an embodiment. As an example, this optical fiber can be the same as or similar to the optical fiber 202 shown in FIG. 4. FIG. 9 shows another exemplary fiber improvement system 600 configured to remove defects in a length of ZBLAN fiber. In some embodiments, system 600 can be used to perform process 500. Accordingly, in the following paragraphs, process 500 will be described in relation to system 600 for ease of explanation. However, it should be understood that in other embodiments, process 500 can also be implemented using other systems or devices capable of annealing ZBLAN fiber.

[0077] Referring first to FIG. 9, according to an embodiment, fiber improvement system 600 includes an acceleration chamber 602 and an annealing unit 604 movably disposed within chamber 602 and configured to process a given length of optical fiber 606. Optical fiber 606 includes a ZBLAN fiber core and a cladding disposed around the fiber core and is substantially the same as or identical to the optical fiber 202 shown in FIG. 4. Acceleration chamber 602 can be configured to mimic a microgravity environment by placing annealing unit 604 (also referred to as a “spindle”) in a free-fall state for a predetermined time (e.g., the second period t2 shown in FIG. 5). In one exemplary embodiment, acceleration chamber 602 is about 0.5 meters in height and is configured to provide about 320 milliseconds of free fall to process a segment of optical fiber 606 that is about 3 inches in length.

[0078] As shown in FIG. 9, the annealing unit 604 has a generally cylindrical shape including a central opening for receiving the optical fiber 606. Further, the annealing unit 604 includes a clamping system 608 and a heating chamber 612 disposed adjacent to each other within the central opening, as will be described in more detail herein with respect to FIG. 11. In an embodiment, the clamping system 608 can be configured to grip or hold a given segment 606a of the optical fiber 606 within the hollow interior 613 of the heating chamber 612 as the annealing unit 604 free-falls through the acceleration chamber 602. The clamping system 608 can be configured to release the processed segment 606a when the segment 606a has been sufficiently processed (annealed and quenched) and grip a new or next segment of the optical fiber for processing. This release and gripping operation can be performed at any appropriate time or at any appropriate position of the acceleration chamber 602, such as when the annealing unit 604 returns to the top or starting position of the acceleration chamber 602, after the annealing unit 604 reaches the top, or while the annealing unit 604 is still present at the bottom of the chamber 602. In this way, each drop and free-fall acceleration of the annealing unit 604 can be used to process the optical fiber 606 segment by segment.

[0079] As shown, system 600 further includes a first spool 614 configured to hold or store the length of the optical fiber 606 before annealing, and a second spool 616 configured to hold or store the length of the optical fiber 606 after annealing. As will be described in more detail herein, system 600 also includes one or more processors 618 (also referred to herein as "processor 618") configured to control the operation of one or more components of system 600, such as, for example, acceleration chamber 602, annealing unit 604, heating chamber 612, clamping system 608, and / or spools 614, 616. In some embodiments, one or more processors 618 are configured to execute process 500 shown in FIG. 8 to improve the optical fiber 606 according to the techniques described herein, or to otherwise control the components of system 600.

[0080] As shown, the first spool 614 can be disposed adjacent to the inlet of the acceleration chamber 602, and the second spool 616 can be disposed adjacent to the outlet of the acceleration chamber 602. During operation, the first spool 614 can be rotated in a first direction so that the optical fiber 606 can move from the first spool 614 onto the second spool 616 through the acceleration chamber 602 after being processed. As shown, the fiber 606 passes through the entire chamber 602 in which the annealing unit 604 and the heating chamber 612 are disposed. In some cases, the second spool 616 and / or the first spool 614 can be rotated in a second direction opposite the first direction to move the optical fiber 606 in the reverse direction through the acceleration chamber 602, for example, if a segment of the fiber 606 needs to be reprocessed or further improved as described herein.

[0081] Referring further to FIGS. 10A-10C, the annealing unit 604 has a generally annular outer wall 619 that extends between an upper end 615 and a lower end 617 of the unit 604, and has an open center 620 configured to house the heating chamber 612 and the clamping system 608. In some embodiments, the distance y between the upper end 615 and the lower end 617 is about 3 inches. In other embodiments, the annealing unit 604 can be longer or shorter, for example, depending on the height of the acceleration chamber 602 and / or the length of the optical fiber 606 to be processed within a given cycle. Although not shown, the heating chamber 612 can be coupled to at least one of the upper opening end 615, the lower opening end 617, and / or the outer wall 619 of the annealing unit 604.

[0082] The heating chamber 612 can be configured to receive the optical fiber 606 through the hollow interior 613 as the optical fiber 606 passes through the annealing unit 604. The hollow interior 613 can be defined by an upper opening end that receives the fiber segment into the chamber 612 and a lower opening end through which the fiber segment can exit the chamber 612. The heating chamber 612 further includes a heating coil or other suitable heating element that can be precisely controlled to a desired temperature. The heating element can be configured to form the hollow interior 613 or otherwise surround the fiber segment 606a disposed within the heating chamber 612. For example, in some embodiments, the heating element can be arranged in an annular shape such that the wall of the heating element forms the hollow interior 613.

[0083] In some embodiments, the heating chamber 612 includes a ceramic heating element. In other embodiments, the heating chamber 612 includes a metal heating element. In one exemplary embodiment, the heating element is configured to have a specific heat capacity of about 0.888 J / g·°C to ensure a rapid temperature change of the heating element. The heating chamber 612 can be configured to heat a given segment of the optical fiber 606 to a first temperature that is higher than the crystallization temperature of the optical fiber 606 and lower than the melting temperature of the optical fiber 606, similar to the heating chamber 412 of FIG. 7B. For example, in some embodiments, the first temperature is about 370°C.

[0084] In some embodiments, the outer wall 619 of the annealing unit 604 extends from the upper end 615 of the opening to the lower end 617 of the opening, is substantially evenly distributed along the entire circumference of the wall 619, and includes a plurality of longitudinal openings 622 that give the annealing unit 604 a basket-like appearance as shown in FIGS. 10A - 10C. (For ease of explanation, FIG. 9 shows an outer wall 619 having a planar surface.) The exact width of each opening 622 can depend on the circumference of the outer wall 619, the desired number of openings 622, or the desired solid-to-space ratio of the outer wall 619. In some embodiments, the heating chamber 612 can also have a partially open (or non-solid) structure. The opening walls of the annealing unit 604 and / or the heating chamber 612 can be configured to enable the air flow through the annealing unit 604 during the cooling portion of the process 500 to rapidly cool the heated segments of the fiber 606. During such a period, the heating chamber 612 can be configured to turn off the heating element so that a given fiber segment 606a is no longer heated to the first temperature. In some embodiments, the air passing through the openings 622 of the annealing unit 604 and / or the heating chamber 612 when the annealing unit 604 is in free fall can be sufficient to rapidly cool the fiber segment 606a to a second temperature that is lower than the crystallization temperature but higher than the glass transition temperature. For example, the second temperature can be about 350 °C, or can be about 10 °C - 20 °C lower than the first temperature. In other embodiments, the annealing unit 604 can be configured to enable a suitable gas or liquid to flow through the opening walls of the annealing unit 604 and / or the heating chamber 612 for such rapid cooling purposes.

[0085] Figures 11A and 11B are partial enlarged views of the interior of annealing unit 604 with the walls of annealing unit 604 and heating chamber 612 removed to better illustrate exemplary clamping system 608. As shown, clamping system 608 includes two movable components 624 disposed opposite one another (or on opposite sides of heating chamber 612) and adjacent to the hollow interior 613 of heating chamber 612. The two components 624 are pivotally coupled to outer wall 619 and / or heating chamber 612 and configured to move between the non-operating position shown in FIG. 11A and the operating position shown in FIG. 11B. Also, as shown, the two movable components 624 are disposed adjacent to fiber segment 606a disposed within heating chamber 612 and configured to engage or compress both sides of fiber segment 606a when in the operating position and to leave fiber segment 606a non-contact when in the non-operating position.

[0086] According to an embodiment, each movable component 624 (also referred to as an "actuator") includes a gripping portion 626 that engages the fiber segment 606a when moved to the actuated position. In some instances, each gripping portion 626 includes a pad, cushion, or other suitable component that enables the movable component 624 to compress the fiber 606 without causing damage. The gripping portion 626 can be configured to apply sufficient frictional force to the fiber segment 606a to maintain or hold the segment 606a within the heating chamber 612 while the clamping system 608 is actuated. For example, in some instances, the first spool 614 and / or the second spool 616 can apply a downward force to the optical fiber 606 sufficient to continuously pull the fiber 606 toward the second spool 616. In such an instance, the gripping portion 626 must be configured to counteract this downward force, for example, by applying sufficient frictional force as a whole to overcome this downward force or by otherwise preventing the fiber 606 from moving or sliding toward the second spool 616. In this way, a given fiber segment 606a can be fixed (or captured) within the heating chamber 612 to enable processing while in the actuated position.

[0087] In contrast, when the clamping system 608 is in the non-actuated or rest position, the components 624 are arranged substantially parallel to each other and to the fiber 606 such that the gripping portion 626 is positioned a certain distance away from the fiber segment 606a to avoid contact with the fiber segment 606a. In such a rest position, the fiber 606 is free to move through the heating chamber 612 and the remainder of the annealing unit 604.

[0088] In some embodiments, a gripping portion 626 (also referred to as a “gripper” or “stopper”) is disposed at or near the lower end of each movable component 624. For example, in FIG. 11A, the component 624 terminates at the gripping portion 626. In such cases, an operating position can be achieved, for example, by pressing or moving the lower end of each component 624 inwardly as shown in FIG. 11B. In other embodiments, the gripping portion 626 can be disposed at or near the upper end of each movable component 624, in which case the gripping portion 626 can be actuated by pressing the upper end of each component 624 inwardly. Other types of devices that grip a segment of the optical fiber 606 during processing and hold the fiber segment within the heating chamber 612 are also envisioned.

[0089] In an embodiment, the clamping system 608 can be configured to stay on one fiber segment 606a during each free fall cycle, i.e., when the annealing unit 604 moves from the top of the acceleration chamber 602 to the bottom of the chamber 602. The clamping system 608 can be configured to release a given fiber segment 606a when it reaches the bottom and grip a second or next segment of the fiber 606. For example, if the heating chamber 612 is configured to process 3 inches of fiber at a time, the clamping system 608 can be configured to grip or clamp the fiber 606 at 3-inch intervals. In this way, the entire length of the optical fiber 606 can be carefully processed or improved using the system 600.

[0090] In an embodiment, the processor 618 can be configured to control one or more functions of the annealing unit 404, the acceleration chamber 402, the spools 614 and 616, and / or other components of the system 600. For example, in some embodiments, the processor 618 is electrically coupled to the first and second spools 614 and 616 to control movement or rotation, including the rotational speed and direction of the spools, in a manner similar to processor control of the spools 414 and 416. In some embodiments, the processor 618 can be electrically coupled to the clamping system 608 to control movement between the actuated and non-actuated positions of the movable component 624.

[0091] The processor 618 can also be electrically coupled to the chamber 612 to control the temperature setting of the heating element within the heating chamber 612. For example, the processor 618 can set the temperature of the heating element to a first temperature during annealing and, to maintain the first temperature during free fall, can raise or lower this temperature as needed based on real-time temperature readings, for example, from a sensor (e.g., a thermocouple) within the chamber 412.

[0092] In some embodiments, the processor 618 can be electrically coupled to the acceleration chamber 602 to control the start of a processing cycle or the release of the annealing unit 604 at the upper end of the chamber 602, and the deceleration and stop of the annealing unit 604 at the end of the cycle or upon reaching the lower end of the chamber 602. For example, the acceleration chamber 602 can include a frictionless track (not shown) or other device that can move the annealing unit 604 up and down within the acceleration chamber 602, and a braking system (not shown) that can stop the movement of the annealing unit 604 along the track. In such cases, the processor 618 can be electrically coupled to the braking system to stop the movement of the annealing unit 604 at the bottom of the chamber 602, and can be electrically coupled to the track system to move the annealing unit 604 in a first direction towards the bottom of the unit 604 and a second opposite direction towards the top of the unit 604. Other devices or systems for moving the annealing unit 604 within the acceleration chamber 602 are also envisioned.

[0093] In some embodiments, system 600 further includes one or more components that perform post-annealing analysis of processed segment 606a to determine whether further processing is needed to obtain optimal results. In such cases, system 600 can include one or more lasers and photodetectors similar to those included in annealing unit 404. Further, processor 618 can be electrically coupled to these components, similar to processor 418, to monitor or measure the scattering profile of processed segment 606a (after completion of the cooling process) and to be configured to determine, in real time, the fiber loss value of processed segment 606a based on the measurement information. Processor 618 can compare the determined fiber loss value to a fiber loss threshold and, if the threshold is not met, can return fiber segment 606a to acceleration chamber 602 for further processing. In one example embodiment, processor 618 can repeat the annealing and cooling processes until an optimal scattering coefficient or other fiber loss metric (e.g., 0.1 decibels per kilometer (dB / km) at approximately 650 nm) for a given optical wavelength is achieved.

[0094] Next, referring again to FIG. 8, process 500 will be described with reference to the components of system 600. Process 500 can be executed using one or more processors included in system 600, such as processor 618. As shown, process 500 starts at block 502 and fixes a segment of an optical fiber (e.g., fiber segment 606a) within an annealing unit (e.g., annealing unit 604). Specifically, a clamping system (e.g., clamping system 608) disposed adjacent to the heating chamber can be used to fix the fiber segment within the heating chamber (e.g., heating chamber 612) of the annealing unit or adjacent to the heating element of this heating chamber. The clamping system can be configured to fix or grip a fiber segment of a uniform length (e.g., 3 inches) for each processing cycle (e.g., annealing and cooling). At block 504, the fiber segment is heated to a first temperature that is higher than the crystallization temperature (T x ) of the optical fiber but lower than the melting temperature (T m ) of the fiber. For example, the first temperature can be about 370 °C or any other value between 352 °C and 450 °C.

[0095] At block 506, the annealing unit is dropped or moved from the first position or start position of the acceleration chamber (e.g., acceleration chamber 602) to the second position or end position of the same chamber with a gravitational acceleration (e.g., 9.8 m / s 2 ) or using free fall motion. In an embodiment, acceleration chamber 602 is configured to maintain free fall motion for a minimum time (e.g., 320 milliseconds). At block 508, the temperature of the fiber segment is maintained at the first temperature for a first period during this free fall motion. At block 510, the fiber segment is cooled to a second temperature for a second period. The second temperature is below the crystallization temperature (T x ) but above the glass transition temperature (T g) can be at a temperature that exceeds. In one example embodiment, the second temperature is about 350 °C, or about 10 °C to 20 °C lower than the first temperature. When the second period ends, the fiber treatment cycle can be considered complete.

[0096] According to an embodiment, the second period (also referred to herein as the "cooling period") begins while the fiber segment is in free fall motion, but can end after the free fall motion stops or while the fiber segment is decelerating (e.g., within the third period t3 of FIG. 5). Thus, the time allotted for free fall can be spent on heating the fiber segment and at least partially cooling it. In some embodiments, the first period and the second period can be of substantially equal length. In other embodiments, the second period can be longer than the first period. As will be understood, the exact length of the first period depends on the physical length of the fiber segment and other factors described herein.

[0097] In block 512, the annealing unit is returned from the second position of the acceleration chamber 602 to the first position of the chamber 602. In block 514, one or more processors of the system 600 (e.g., processor 618) determine whether the processed fiber segment meets a fiber loss threshold stored in the unit's memory. If the determination in block 514 is "no" (i.e., the threshold is not met), the process 500 returns to block 504 and begins processing the fiber segment again (i.e., repeats blocks 504-514). If the determination in block 514 is "yes" (i.e., the threshold is met or exceeded), the process 500 proceeds to block 516.

[0098] In block 516, one or more processors determine whether there are remaining subsequent fiber segments in the fiber pool before annealing (e.g., the first pool 614). If the determination in block 516 is "no", process 500 ends. If the determination in block 516 is "yes", process 500 proceeds to block 518 and releases the processed fiber segments from the heating chamber of the annealing unit. For example, one or more processors can release the gripping of the fiber by the clamping system or shift it to an inactive state. Process 500 returns from block 518 to block 502 and begins processing the next fiber segment. Thus, process 500 can repeat any number of times until the entire length of the fiber before annealing is sufficiently improved or until a target fiber loss threshold (e.g., less than 0.1 dB / km at 650 nm) is met.

[0099] In an embodiment, each of processes 300 and 500 can be implemented at least in part by at least one data processor that executes software stored in a memory, such as processor 418, and a memory (not shown) included in annealing unit 404 shown in FIG. 7B, or by processor 618 and a memory (not shown) included in acceleration chamber 602 shown in FIG. 9. Processor 418 / 618 can interact with one or more other components of system 400 / 600, respectively, to perform the operations of a given process 300 / 500. Processor 418 / 618 can be any suitable hardware device that executes software instructions retrieved from a memory, such as a central processing unit (CPU), a semiconductor-based microprocessor (in the form of a microchip or chipset), or another type of microprocessor.

[0100] Each processor 418 / 618 is communicatively coupled to a memory that can be any suitable memory device suitable for storing software instructions, such as, for example, a volatile memory device (e.g., a random access memory (RAM) such as DRAM, SRAM, SDRAM, etc.), a non-volatile memory device (e.g., ROM, hard drive, tape, and CD-ROM, etc.), or any combination thereof. Further, the memory can incorporate an electronic storage medium, a magnetic storage medium, an optical storage medium, and / or other types of storage media. In some embodiments, the memory includes a non-transitory computer-readable medium that implements all or part of one or more of the methods described herein and shown in FIGS. 5 and 8. The memory can store one or more executable computer programs or software modules that include a set of instructions to be executed, such as, for example, one or more software applications that the processor 418 / 618 can execute to implement the principles disclosed herein (e.g., process 300 / 500). The executable program can be executed in software, firmware, hardware, or any combination thereof.

[0101] FIG. 12 shows an exemplary optical fiber power feeding system 700 according to an embodiment. The components of system 700 can be the same as those of the optical fiber power feeding system 100 shown in FIG. 3. For example, system 700 can include a light source 702 that is substantially the same as light source 102 of FIG. 3, an optical fiber cable 704 that is substantially the same as optical fiber cable 104 of FIG. 3, and a photodetector 706 that is substantially the same as photodetector 106 of FIG. 3. In some embodiments, the optical fiber cable 704 can have a first end 708 coupled to the light source 702, a second end 710 coupled to the photodetector 706, and a plurality of optical fibers extending along the length of the cable 704, i.e., the total length between the first end 708 and the second end 710, and being substantially the same as, for example, the ZBLAN optical fiber 202 shown in FIG. 4. For the sake of brevity, the photodetector 706, the light source 702 (also referred to as a "laser light source"), and the optical fiber cable 704 will not be described in detail here in light of their similarities.

[0102] In an embodiment, the optical fiber power feeding system 700 can be used in or included in an optical fiber network that supplies power to various loads, each connected to or including such an opto - electrical converter. For example, the optical fiber network can terminate at various machines and equipment in industrial applications, or at various electronic devices and other devices powered using standard wall outlets in residential or commercial applications. An example of such a network can be the optical power distribution system 800 shown in FIG. 13.

[0103] In some embodiments, the optical fiber cable 704 can be coupled to the light source 702 and / or the photodetector 706 via respective optical fiber couplers or connectors 712 and 714 and optical fiber splices 716 and 717 (e.g., mechanical splices, fusion splices, or any other suitable type of splicing device). For example, as shown in FIG. 12, the first end 708 of the cable 704 can be coupled to a first splice 716 that can be connected to a first connector 712 via a second optical fiber cable 713 similar to the optical fiber cable 704. The first connector 712 is also coupled to the light source 702 and is configured to transfer or transmit optical energy or optical power from the light source 702 to the optical fiber cable 713 and / or 704. Similarly, the second end 710 of the cable 704 can be coupled to a second splice 717 that can be connected to a second connector 714 via a third optical fiber cable 715 similar to the optical fiber cable 704. The second connector 714 is also coupled to the photodetector 706 and is configured to transfer the optical power received via the optical fiber cable 715 and / or 704 to the photodetector 706. As will be appreciated, additional splices 716 can be included if more optical fiber cables are joined together to supply power via the optical fiber power supply system 700.

[0104] As shown in FIG. 12, the light source 702 is included in a transmission unit 718 (also referred to herein as an electro-optical (E-O) conversion unit) and is configured to convert electrical energy into optical energy (e.g., high-power laser energy) for transmission via an optical fiber cable 704, similar to the light source 102 in FIG. 1. In an embodiment, the electrical energy is power received from an external power source (e.g., a DC power source, an AC power source, etc.) coupled to the transmission unit 718. The transmission unit 718 also includes a driver 720 (e.g., a laser diode driver) coupled between a power source and the light source 702 that uses a power signal received from the power source (or other power input) to drive the operation of the light source 702 (e.g., a laser diode). In some embodiments, the transmission unit 718 can be coupled to an external control device (e.g., the power control unit 836 shown in FIG. 13) that serves as an intermediary device between the transmission unit 718 and the external power source. In such a case, the external control device can manage the amount of power supplied to the transmission unit 718 and control other operational aspects of the unit 718, for example, according to the method 900 of FIG. 14.

[0105] As shown in FIG. 12, the photodetector 706 is included in a receiving unit 722 (also referred to herein as an opto-electrical (O-E) conversion unit) and is configured to convert optical energy (or power) received via the optical fiber cable 704 into electrical energy (or power). In an embodiment, this electrical energy is used, for example, as shown in FIG. 13, to power one or more electrical loads coupled to the receiving unit 722.

[0106] In an embodiment, the receiving unit 722 is also configured to transmit a control signal, a status signal, a feedback signal, and / or other data signals to the transmitting unit 718 via the same optical fiber cable 704 coupled between the receiving unit 722 and the transmitting unit 718. The information included in such data signals can be received from one or more electrical loads coupled to the receiving unit 722 (e.g., as described with respect to FIG. 13), or from a control unit (not shown) coupled to a plurality of electrical loads. In such an embodiment, the optical fiber cable 704 can include one or more optical circulators (not shown) that enable bidirectional optical signal transmission through the entire cable 704 or through one or more of the individual fibers included in the cable 704, or can be coupled to such optical circulators.

[0107] As shown, the receiving unit 722 can further include a first processor 724 (e.g., a microprocessor, a microcontroller, or the like) configured to generate one or more digital data signals based on the received information. The receiving unit 722 can also include an optical transmitter 726 coupled to the first processor 724 and the optical fiber cable 704. The optical transmitter 726 can be configured to convert the digital data signals into optical data signals or other signals that can be transmitted via the optical fiber cable 704. The optical transmitter 726 can be further configured to supply the optical data signals to the optical fiber cable 704 for transmission to the transmitting unit 718. The optical transmitter 726 can be a laser diode (or diode laser), or any other optical device capable of transmitting optical data signals via the optical fiber cable 704. In some embodiments, the optical transmitter 726 is a laser diode included in the photodiode package of the optical detector 706.

[0108] Similarly, the transmission unit 718 can further include an optical receiver 728 coupled to the optical fiber cable 704 and a second processor 730 (e.g., a microprocessor, a microcontroller, or the like) similarly included in the transmission unit 718. The optical receiver 728 can be configured to receive an optical data signal transmitted via the optical fiber cable 704 and convert the received signal back into digital form. The optical receiver 728 can be a photodiode or other optical device that can monitor the optical cavity of the laser diode 702 for the optical data signal. In some embodiments, the optical receiver 728 is a monitor diode incorporated into the laser diode package of the light source 702. The optical receiver 728 can supply a digital data signal to the second processor 730 for processing as described, for example, with respect to FIG. 13. In an embodiment, the second processor 730 can supply data extracted from the optical data signal to an external device such as a controller or control unit of an external power source (e.g., as shown in FIG. 13).

[0109] Next, FIG. 13 shows an exemplary optical power distribution system 800 that uses an optical fiber cable described herein (e.g., as shown in FIG. 4) according to an embodiment as a transmission line for transmitting optical power in the form of high output laser energy to a plurality of locations or loads. The optical power distribution system 800 can be used to distribute power over long distances (e.g., between continents, between countries, between cities, etc.) and / or in highly unstable areas where there is a risk of power distribution in any industrial, commercial, residential, or personal environment, including, for example, within an aircraft, within an automobile, or within a residence.

[0110] In an embodiment, the optical power distribution system 800 can include n optical fiber power feeding systems 801, each of which is substantially the same as the optical fiber power feeding system 700 shown in FIG. 12. For example, as shown in FIG. 13, the system 800 can include a plurality of electro-optical ( "E-O") conversion units 818, a plurality of opto-electrical ( "O-E") conversion units 820, and a plurality of optical fiber cables 804. Each E-O unit 818 is substantially the same as the transmission unit 718 of FIG. 12, each O-E unit 822 is substantially the same as the reception unit 722 of FIG. 12, and each optical fiber cable 804 is substantially the same as the optical fiber cable 704 of FIG. 12. Further, each E-O unit 818 can be coupled to each respective O-E unit 822 of the O-E units 822 via a corresponding optical fiber cable 804, and can be configured to transmit optical power ( "OPP") to each respective O-E unit 822 via this cable 804 in the same manner as in the case of the optical fiber power feeding system 700. For the sake of brevity, the E-O units 818, the O-E units 822, and the optical fiber cables 804 will not be described in detail here in view of their similarity to FIG. 12.

[0111] As shown in FIG. 13, each optical fiber power feeding system 801 can be coupled to each electrical load 832 of a plurality of electrical loads 832 and a common power supply 834. Also, each of the plurality of E-O units 818 can be coupled to a power control unit 836 (or power controller) electrically connected to the power supply 834. The power supply 834 can be any type of power supply (e.g., DC or AC) or any other device that can generate sufficient power to support the electrical loads 832. The power control unit 836 (also referred to as the "master power control unit") manages the distribution or transmission of the power generated by the power supply 834 to the E-O units 818 and can control various other aspects of the power distribution system 800 as described herein. FIG. 13 shows a single power supply 834 that generates power and a single power control unit 836 coupled thereto, but in other embodiments, the system 800 can include multiple power supplies and / or multiple control units coupled to the plurality of E-O units 818.

[0112] According to an embodiment, the power control unit 836 is configured to control the operation of the power supply 834 (e.g., on or off, increase or decrease in the amount of power generated), and / or the operation of each E-O unit 818 (e.g., on or off), and / or manage the power distribution to the individual E-O units 818, and / or control other aspects of the power distribution system 800. In some cases, the power control unit 836 manages the power distribution by evenly distributing the generated power among all the E-O units 818. In other cases, the power control unit 836 is configured to optimize the distribution of the generated power among the E-O units 818 based on the electrical loads 832 coupled to each E-O unit 818.

[0113] For example, the power control unit 836 can adjust or control the optical power distributed to a given O-E unit 822 according to the power rating or power requirement of the corresponding electrical load 832 (i.e., the load 832 electrically connected to the O-E unit 822), or other status information received from the load 832. In such a case, the power control unit 836 determines the power requirement of each electrical load 832 based on the data provided by the electrical load 832, and accordingly controls one or more characteristics of the optical power output by each corresponding E-O unit 818 such that the power finally received at the corresponding electrical load 832 matches or conforms to the power requirement of the load 832.

[0114] The electrical load 832 can be any type of device or system that requires power, including, for example, a residence or building, an electronic device, a power plant, a vehicle, and others. Each electrical load 832 can be electrically coupled to its respective O-E unit 822 using a wired connection (e.g., an electrical cable or the like) or a wireless connection (e.g., a wireless power transfer system). In an embodiment, each electrical load 832 can be configured to transmit data to the O-E unit 822 connected to this load 832 using, for example, the same wired or wireless connection, or another link or connection for data transmission. The data can include status information regarding the management of the power supply, connection information, power requirement information, and / or any other information. The status information can include, for example, the power factor of the electrical load 832 (or the ratio of the active power to the apparent power), the power utilization rate indicating the energy efficiency of the load 832 or other measurements, and any other information regarding the operation or state of the load 832. The connection information can include, for example, a connection validator or other indication that the load 832 is connected to the O-E unit 822 and / or is receiving power from the O-E unit 822, and any other information regarding the electrical connection between the load 832 and the O-E unit 822. The power requirement information can include, for example, the power rating of the electrical load 832, or the amount of power required to operate or otherwise support the load 832, and any other information regarding the power-related needs of the load 832.

[0115] Referring further to FIG. 12, the O-E unit 822 can be configured to receive data provided by the electrical load 832 and process the received data using individual processors (e.g., the processor 724 of FIG. 12) or other computer devices included in the unit 822. The O-E processor can be further configured to generate a data signal (or digital data signal) based on the received data and supply the data signal to an optical transmitter (e.g., the optical transmitter 726 of FIG. 12) that transmits the data to the E-O unit 818. As described with respect to FIG. 12, the optical transmitter can convert the digital data signal into an optical data signal (also referred to herein as an optical status signal (“OSS”)) suitable for transmission via an optical fiber cable 804 as shown in FIG. 13.

[0116] In an embodiment, the power control unit 836 can be configured to analyze each data signal ("OSS") received from the E-O unit 818 to determine whether the optical power supplied to each electrical load 832 meets the power requirements of this load 832, or to identify any power or load shedding needs of the system 800. For example, if a given electrical load 832 requires more optical power than the optical power ("OPP") currently being supplied, the power control unit 836 can determine whether it can supply additional optical power to this O-E unit 822 by increasing the number of optical fibers in the optical fiber cable 804 used to transmit optical power to the corresponding O-E unit 822. In addition to or instead of this, the power control unit 836 can also determine whether the power source 834 can supply more generated power to the corresponding E-O unit 818 to increase the total amount of power available to the load 832. In other cases, the power control unit 836 can control or adjust other characteristics of the E-O unit 818 and / or the optical power transmitted from the E-O unit 818 to increase the amount of power supplied to the load 832. In any case, if additional power is available, the power control unit 836 can control the E-O unit 818 and / or the power source 834 to ensure that additional power is supplied to each electrical load 832 as needed.

[0117] For example, if all the optical fibers of the optical fiber cable 804 are already in use and no additional power is available because the power source 834 is already operating at maximum capacity, the power control unit 836 can determine that the power source 834 cannot meet the power requirements of a given electrical load 832, and as a result, can terminate the optical link between the corresponding E-O unit 818 and the O-E unit 822. For example, the power control unit 836 can turn off the light source included in the corresponding E-O unit 818, or stop the transmission of optical power via the optical fiber cable 804 coupled to the E-O unit 818.

[0118] In some embodiments, the power control unit 836 can be configured to use techniques similar to those described herein even when the amount of power required by the load 832 is less than the amount of power being supplied. For example, the power control unit 836 can reduce the number of optical fibers being used, reduce the amount of generated power supplied by the power source 834 to the laser light source of the E-O unit 818, reduce the amount of optical power output by the E-O unit 818, and / or control one or more other characteristics of the E-O unit 818 and / or the optical fiber cable 804.

[0119] Accordingly, the system 800 avoids inefficiencies in the power grid by matching the power requirements of each load 832, but can also be configured to use power limiting techniques as further described herein with respect to the method 900 of FIG. 14 to prevent charge buildup and ensure efficient utilization of the O-E / E-O infrastructure.

[0120] The power control unit 836 can include one or more suitable hardware devices that perform the operations described herein, such as, for example, a processing device (or processor) and a memory device. The processor can be any suitable hardware device that executes software instructions retrieved from a memory device, such as, for example, a central processing unit (CPU), a semiconductor-based microprocessor in the form of a microchip or chipset, or another type of microprocessor.

[0121] The memory device can be any suitable memory device for storing software instructions, such as, for example, a volatile memory element (e.g., a random access memory (RAM) such as DRAM, SRAM, SDRAM, etc.), a non-volatile memory element (e.g., ROM, hard drive, tape, and CD-ROM, etc.), or any combination thereof. Further, the memory device can incorporate an electronic storage medium, a magnetic storage medium, an optical storage medium, and / or other types of storage media. In some embodiments, the memory includes a non-transitory computer-readable medium that implements all or part of one or more of the methods described herein and shown in FIG. 14. The memory can store one or more executable computer programs or software modules that include a set of instructions to be executed, such as, for example, one or more software applications that a processor can execute to implement the principles disclosed herein (e.g., process 900). The executable program can be executed in software, firmware, hardware, or any combination thereof.

[0122] FIG. 14 shows an exemplary power supply management process or method 900 in an optical fiber power supply system that includes a transmitting unit having a laser light source, a receiving unit having a photodetector, and an optical fiber cable coupled between these units. In some embodiments, the optical fiber power supply system can be substantially similar to any of the optical fiber power supply systems described herein, such as, for example, the optical fiber power supply system 700 shown in FIG. 12. In some embodiments, the optical fiber power supply system can be an optical power distribution system, such as, for example, the optical power distribution system 800 shown in FIG. 13, or can form part of a larger optical power distribution system (e.g., similar to the optical fiber power supply system 801 in FIG. 13).

[0123] Method 900 can be performed by one or more electronic devices or components of the optical fiber power supply system either alone or in combination with one or more other electronic devices. These devices can include, for example, the power control unit 836 shown in FIG. 13, the transmission unit 718 shown in FIG. 12, and / or the reception unit 722 shown in FIG. 12. The functions of method 900 can be at least partially implemented by a processor of the device (e.g., the processor of the power control unit 836 and / or processors 724 and 730 of FIG. 12) that executes a software application stored in the memory of the device. In some embodiments, the application can be a computer program stored on a non-transitory computer-readable medium that can be executed by the processor of the device. The (single or multiple) electronic devices can not only employ one or more internal devices (e.g., the laser light source 702 and the optical receiver 728 of the transmission unit, the photodetector 706 and the optical transmitter 726 of the reception unit 722, etc.) to further execute the operations of method 900, but also interact or cooperate with one or more external devices or components coupled to the electronic device, such as an external power source (e.g., the power source 834 in FIG. 13) and an external electrical load (e.g., the electrical load 832 in FIG. 13). In some embodiments, the power control unit 836 can execute method 900 to manage the power supply in each optical fiber power supply system 801 included in the optical power distribution system 800.

[0124] As shown in FIG. 14, method 902 can start from step 902, which includes transmitting high-output laser energy from a transmitting unit to a receiving unit using a first number n of optical fibers included in an optical fiber cable. In an embodiment, the optical fiber cable includes a plurality of optical fibers each extending along the length of the optical fiber cable and surrounded by a thermal filler. For example, the optical fiber cable can be substantially the same as the optical fiber cable 200 shown in FIG. 4 and can be composed of an optical fiber 202 or any other optical fiber cable that can transmit laser energy having a power of about 1 gigawatt over a distance of about 1000 kilometers (km) with a loss of about 0.1 decibel (dB). In such an embodiment, the transmitting unit can transmit optical power to the receiving unit using all, some, or any other number of optical fibers within the optical fiber cable. In some embodiments, the transmitting unit is configured to first use a first number of optical fibers selected based on a preset value (e.g., one fiber, 50% of the fibers, etc.). In other embodiments, the user or operator of the system can select the first number of optical fibers.

[0125] Step 904 of method 900 includes receiving, in a processor, a data signal including information regarding the power requirements of an electrical load coupled to a receiving unit, the data signal being transmitted from the receiving unit to the transmitting unit using the same optical fiber cable used for transmitting the high-output laser energy. The power requirement information can include, for example, the power rating of the electrical load or other things indicating the amount of power required to operate the electrical load. In some embodiments, the data signal can also include additional information such as connection information verifying the power supply to the electrical load, status information indicating the power factor or power utilization rate of the electrical load, or other things indicating the amount of power used by or received at the load, feedback information including a message from the electrical load and / or the receiving unit, and / or other information described herein.

[0126] According to an embodiment, the data signal is an optical data signal generated by an optical transmitter (e.g., the optical transmitter 726 in FIG. 12) included in the receiving unit and transmitted via an optical fiber cable. In such an embodiment, step 904 further includes receiving the optical data signal at an optical receiver (e.g., the optical receiver 728 in FIG. 12) included in the transmitting unit. In step 906, the optical data signal is converted into a digital data signal using, for example, an optical receiver (e.g., a monitor diode) and supplied to a processor.

[0127] In an embodiment, method 900 further includes analyzing the data signal using a processor and, based on this analysis, controlling the high-power laser energy output by the transmitting unit. For example, when the data signal includes power requirement information of an electrical load, method 900 includes controlling the high-power laser energy output by the transmitting unit based on the power requirement of the electrical load. In various embodiments, method 900 includes adjusting or controlling one or more characteristics of the transmitting unit and / or the optical fiber cable to control the high-power laser energy output.

[0128] Specifically, the analysis of the data signal can include, in step 908, identifying the power requirement information included in the data signal and determining whether the power requirement included in the data signal exceeds a threshold power amount. In some embodiments, the threshold power amount can be related to an external power source (e.g., the power source 834 in FIG. 13) coupled to the transmitting unit, such as, for example, the maximum power amount that the external power source can generate, or other thresholds of the external power source. In other embodiments, the threshold power amount can be related to a light source (e.g., a laser light source) of the transmitting unit, such as, for example, the maximum optical power amount that the laser can output, or other thresholds of the light source. In still other embodiments, the threshold power amount can be related to the optical fiber cable, such as, for example, the maximum power amount that the cable can carry over its entire length, or other thresholds of the optical fiber cable. Other threshold amounts related to the optical fiber power supply system are also envisioned.

[0129] If the determination in step 908 is affirmative, that is, if the power requirement of the electrical load exceeds the threshold amount of electrical energy, method 900 proceeds to step 910, which includes controlling the high-power laser energy output transmitted by the transmitting unit by interrupting the transmission of high-power laser energy from the transmitting unit. That is, when the power required for the operation of the electrical load is greater than the available amount of electrical energy, the optical fiber power feeding system interrupts the operation of the light source or otherwise stops the supply of optical power via the optical fiber cable.

[0130] If the determination in step 908 is negative, that is, if the power requirement does not exceed the threshold, method 900 proceeds to step 912, which includes determining whether the high-power laser energy output by the transmitting unit or received by the receiving unit satisfies the power requirement of the electrical load. For example, the processor can compare the amount of optical power detected by the receiving unit with the amount of electrical power required for the operation of the electrical load to determine whether there is a gap or deficiency on the receiving side. If the determination in step 912 is affirmative, that is, if the power requirement of the electrical load is satisfied, method 900 can end.

[0131] On the other hand, if the determination in step 912 is negative, that is, if the received laser energy does not satisfy the power requirement, method 900 can include controlling or adjusting the high-power laser energy output by the transmitting unit so that the power requirement is satisfied, or otherwise adjusting the laser output to meet the needs of the corresponding electrical load. The exact method of adjusting the laser energy output of the transmitting unit varies depending on various factors, including, for example, the power requirement of the electrical load, the total number of optical fibers included in the optical fiber cable, the power characteristics of the laser light source, and the maximum power capacity of each fiber.

[0132] In some embodiments, at step 914, the adjustment can be achieved by adjusting the number of optical fibers used for transmitting laser energy from the transmitting unit based on the power requirement of the electrical load so as to control the form of the optical power (OPP) being transmitted via the optical fiber cable. For example, in some cases, the transmitting unit can increase the first number of optical fibers initially used for transmitting laser energy to a second number of optical fibers that is greater than the first number. In other cases, the transmitting unit can decrease the number of optical fibers being used to a third number that is less than the first number in order to reduce the amount of optical power being transmitted to the receiving side. Accordingly, step 914 can further include using a processor to determine the number of optical fibers required to meet the power requirement of the electrical load and instructing the transmitting unit (or the laser light source included in the transmitting unit) to use the determined number of optical fibers for optical power transmission to the receiving unit.

[0133] In some cases, the adjustment of the laser energy output at step 916 can be achieved by adjusting not only the number of optical fibers but also the amount of power transmitted through each optical fiber. As an example, initially, each optical fiber within the first number of fibers can be operated at approximately 75% of the maximum power capacity of the fiber (e.g., about 10 kilowatts (kW)). If more power is required, one or more of these fibers can be operated at a higher capacity (e.g., 80%), or additional fibers can be used up to the capacity required to meet the power requirement. Similarly, if only a small amount of power is required, the total power output can be reduced by controlling or decreasing the amount of optical power transmitted through one or more fibers.

[0134] In some cases, the adjustment in the form of laser energy output or optical power in step 916 can be achieved by adjusting the amount of power output by the laser light source according to the power requirements of the electrical load. For example, in order to increase the amount of optical power transmitted to the receiving unit, the power setting of the laser light source or the optical power conversion setting of the entire transmitting unit can be increased or adjusted from a first setting to a second setting. As another example, in an embodiment where the laser light source is a diode array composed of a plurality of laser diodes, the laser energy output of the laser light source can be adjusted by controlling the number of laser diodes used to output optical power. For example, the transmitting unit can be configured to turn on or off one or more of the laser diodes in the array according to the amount of power required to meet the power requirements of the electrical load.

[0135] In some cases, the combination of steps 914 and 916 can be used to meet the power requirements of the electrical load. For example, if the power requirements of the electrical load are not met even when all the optical fibers in the optical fiber cable are used, the amount of optical power output by the laser light source can also be increased to the maximum power capacity of each fiber. In some cases, while increasing the amount of optical power output by the laser light source, the number of optical fibers used for transmitting laser energy is increased from a first number of fibers to a second number of fibers equal to the total number of optical fibers included in the optical fiber cable, so that the high-power laser energy output by the transmitting unit is controlled or adjusted based on the power requirements of the electrical load.

[0136] In some embodiments, the laser energy output by the transmission unit can be adjusted temporarily or only for a set period of time to meet, for example, peak load requirements (e.g., during the day) or other temporary needs of the fiber optic power supply system. For example, step 914 can further include increasing the number of optical fibers used from a first number to a second number at a first time point (), and decreasing the number of optical fibers back to the first number at a second time point or after the expiration of a set period. Similarly, step 916 can further include increasing the amount of optical power output by the laser light source from a first setting to a second setting at a first time point, and returning the amount of optical power output by the laser light source back to the first setting at a second time point or after the expiration of a certain period to decrease the amount of optical power output. As will be appreciated, other techniques for temporarily adjusting the form of the optical power transmitted through the fiber optic cable can also be used.

[0137] FIG. 15 shows an exemplary optical fiber power supply system 1000 configured for use in medical applications according to an embodiment. In some embodiments, the optical fiber power supply system 1000 can be used to remove or excise tumors or other undesirable objects within the human body without major surgery. As an example, the optical fiber power supply system 100 can be used for laser-induced thermotherapy, percutaneous laser ablation of certain tumors (e.g., primary and metastatic malignant lung tumors and the like), and other suitable medical procedures (e.g., ureteral calculus removal, etc.). The optical fiber power supply system 1000, like other optical fiber power supply systems described herein, can adjust its laser energy output according to these needs, even if the receiving side, or in this case the needs of a particular medical procedure being performed, change throughout the procedure. For example, when the system 1000 is used to excise or eliminate an undesirable object within a patient's body, it can be configured to adjust one or more characteristics of the laser energy output as the size and / or shape of the object changes in response to laser treatment. As a result, the optical fiber power supply system 1000 can provide a more efficient and accurate ablation method than existing laser-induced thermotherapy and the like.

[0138] As shown in FIG. 15, the system 1000 includes a light source 1002 (or laser light source) that emits ultra-high output laser energy, similar to the light source 102 shown in FIG. 3. The system 1000 further includes at least one optical fiber 1004 having a first end coupled to the laser light source 1002. During the ablation procedure, the second end of at least one optical fiber 1004 can be inserted into the body part of the patient 1006 adjacent to the object 1008 to be removed or excised. The optical fiber 1004 can serve as a transmission line that guides high-output laser energy from the laser light source 1002 towards the object 1008. When the procedure is complete, all or part of the optical fiber 1004 can be removed from the patient's body and discarded.

[0139] Generally, the laser energy emitted via the optical fiber 1004 can be adjusted or optimized to achieve ablation of a specific object 1008. For example, the high-power laser energy output by the laser light source 1002 can be configured to have a wavelength of about 2 to 3 micrometers (μm) or other appropriate wavelengths according to the object 1042 to be excised. For example, this wavelength can be set to 2.1 μm for tumor ablation and 2.0 μm for ablation of ureteral stones. In some embodiments, the laser light source 1002 can be configured to emit pulses of laser energy at a specific rate according to the medical treatment and / or the type of the object 1008. For example, the laser light source 1002 can be configured to transmit pulses of laser energy at a repetition rate of 50 Hertz (Hz) during the fragmentation of ureteral stones. Also, the laser light source 1002 can be configured to transmit pulses of optical energy having a specific amount of power (e.g., a pulse output of about 1 joule (J) per pulse) according to a specific medical use.

[0140] In embodiments, the laser energy output is adjusted during the ablation procedure to adjust the high-power laser energy according to not only the specific type of the object 1008 but also the physical structure of the object 1008 that changes as ablation is performed. For example, as the size of the object 1008 decreases and / or as the object 1008 splits into multiple small pieces, the intensity of the laser energy directed at the object 1008 can be reduced. In embodiments, such adjustment can be achieved by controlling one or more features or characteristics of the laser energy output, such as the output level of the laser energy output by, for example, the laser light source 1002. In some cases, such adjustment can be first performed before the start of the treatment, for example, based on information regarding the initial size and / or initial shape of the object 1008, and continued based on status information or feedback information regarding the object 1008 or the remaining part thereof during the treatment.

[0141] For this purpose, the optical fiber power supply system 1000 further includes a spectrometer 1010 coupled to a second optical fiber 1012 having a distal end disposed at or near the same position as the first optical fiber 1004 within the patient 1006 (i.e., adjacent to the object 1008). The second optical fiber 1012 can be configured to return the optical energy detected at the position of the object 1008 to the spectrometer 1010. In an embodiment, the second optical fiber 1012 can be substantially similar to one of the optical fibers 202 shown in FIG. 4. The spectrometer 1010 can be a near-infrared (or "NTR") spectrometer or other optical spectroscopy device that analyzes or measures various characteristics of the return light (or optical pulse) and can determine the state of the object 1008 or other incident object based on this analysis. For example, the spectrometer 1010 can measure the intensity of the return light after the initial application of laser energy and analyze the spectral signature of the return pulse to determine whether the laser energy output completely excised the object 1008, or only a portion of the object 1008, and / or whether the object 1008 was split into multiple small pieces. The spectrometer 1010 can also analyze the signature of the return pulse to determine the size of the remaining fragments of the object 1008. In some cases, the spectrometer 1010 is configured to analyze the return light by identifying the signature of each return pulse and comparing these signatures to the signature of the object 1008 or other prior information previously obtained, and to determine how much, if any, of the original object 1008 remains. The spectrometer 1010 can also monitor the signature of the return pulse, including tissue morphology and absorption characteristics, to evaluate the effectiveness or completeness of the ablation procedure. As will be appreciated, the spectrometer 1010 can identify and analyze the different colors of light and the spectral structure of the return pulse included in the return pulse to make these determinations.

[0142] The optical fiber power supply system 1000 further includes a control unit 1014 that adjusts at least one characteristic of the laser energy output based on the status information determined by the spectrometer 1012. In an embodiment, the control unit 1014 can control one or more characteristics of the optical fiber power supply system 1000 that can affect the intensity of the laser energy directed at the object 1008. For example, the control unit 1014 can be configured to adjust the amount of optical power or optical energy emitted from the light source 1002. As another example, the control unit 1014 can adjust the shape of the laser energy pulses incident on the object 1008 or otherwise vary or affect one or more characteristics of the optical fiber 1004 as described herein for use in transmitting the laser energy toward the patient 1006 as shown in FIG. 16.

[0143] As shown in FIG. 15, in some embodiments, the control unit 1014 is a stand-alone computer device that communicates with both the spectrometer 1012 and the laser light source 1002 via a wired or wireless connection. In other embodiments, the control unit 1014 can be a microcontroller or the like included in the spectrometer 1012, in which case the spectrometer 1012 can communicate with the laser light source 1002. As will be appreciated, nonetheless, the control unit 1014 can include a processor and memory that perform the operations described herein (e.g., similar to those of the receiving unit 722 shown in FIG. 12).

[0144] Furthermore, FIG. 16 shows a cross-sectional view of the optical fiber 1004 included in the optical fiber power supply system 1000 of FIG. 15. In an embodiment, the optical fiber 1004 can be configured to enable control of the pulse shape and / or other characteristics of the laser energy supplied via the optical fiber 1004. As shown, the optical fiber 1004 includes a ZBLAN core 1016 that can be substantially similar to the fiber core 212 shown in and described herein with reference to FIG. 4. The optical fiber 1004 further includes a cladding 1018 disposed around the ZBLAN core 1016. The cladding 1018 can be fused or joined to the core 1016, similar to the cladding 214 of FIG. 4. The optical fiber cable 1004 further includes a protective coating 1020 configured to protect and isolate the ZBLAN fiber core 1016 and the cladding 1018. The coating 1020 can be composed of polyvinyl fluoride (“PVF”) or other suitable polymers.

[0145] In an embodiment, the cladding 1018 and the coating 1020 can be configured to enable specific control or adjustment of one or more characteristics of the laser energy propagating through the core 1016 of the optical fiber 1004. For example, the cladding 1018 can have a periodic structure configured to guide or direct the propagation of the laser energy towards the object 1008. The coating 1020 can be an electroactive polymer whose size or shape can change when stimulated by an electric field, such as the electric field applied to the cladding 1018 by the control unit 1014 in FIG. 15. As the coating 1020 expands and / or contracts in response to the electric field, the period of the periodic structure of the cladding 1018 also changes. Correspondingly, the pulse shape of the laser energy propagating through the core 1016 and the amplitude or intensity of each optical pulse change, and thus the type of light that can pass through the optical fiber 1004 is controlled. In an embodiment, the control unit 1014 can be configured to apply a specific electric field to the cladding 1018 such that the pulse shape and intensity level of the laser energy incident on the object 1008 are adjusted as needed or according to the current state of the object 1008 (e.g., the number and size of the remaining fragments, etc.).

[0146] In some embodiments, the type of the light source 1002 included in the optical fiber power supply system 1000 can be changed or modified according to a specific medical treatment. For example, for the fragmentation of ureteral calculi, a standard Ho:YAG laser can be used in such surgical procedures.

[0147] In some embodiments, the process descriptions or blocks in the figures such as FIGS. 6, 8, and 14 can represent modules, segments, or portions of code that include one or more executable instructions for implementing specific logical functions or logical steps in the process. As will be understood by those skilled in the art, within the scope of the embodiments described herein, other implementations that can execute functions in an order different from that illustrated or described, including executing functions substantially simultaneously or in reverse order depending on the functions involved, are included.

[0148] It should be emphasized that the above-described embodiments, especially any of the "preferred" embodiments, are merely possible examples shown to enable a clear understanding of the principles of the present invention. Many changes and modifications can be made to the above-described (single or multiple) embodiments without substantially departing from the spirit and principles of the technology described herein. All such modifications are intended to be included within the scope of this disclosure and protected by the following claims.

Claims

1. An optical fiber cable, having a length extending between a first end and a second end, a central cooling tube, a plurality of optical fibers arranged radially around the cooling tube, each including a fiber core and a cladding disposed around the fiber core, an outer protective cover, an inner thermal filler disposed between the outer protective cover and the central cooling tube and surrounding each of the optical fibers, comprising: wherein the central cooling tube, the outer protective cover, the inner thermal filler and the plurality of optical fibers each extend along the length of the cable, an optical fiber cable.

2. Each optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN). The optical fiber cable according to claim 1.

3. The optical fiber cable according to claim 1, wherein the thermal filler is made of acrylic.

4. The optical fiber cable according to claim 1, wherein the cooling tube contains a cooling substance configured to keep the temperature of the cable below a threshold temperature.

5. The optical fiber cable according to claim 1, wherein the cooling substance is air.

6. The optical fiber cable according to claim 1, wherein each fiber core has a radius selected from the range of about 300 micrometers (μm) to about 500 μm.

7. The optical fiber cable according to claim 1, wherein the cable can transmit laser energy having a power of about 1 gigawatt over a distance of about 1000 kilometers (km) with a loss of about 0.1 decibel (dB).

8. The optical fiber cable according to claim 7, wherein the laser energy has a wavelength of about 2.1 μm.

9. The optical fiber cable according to claim 1, wherein the length is at least about 50 km.

10. The optical fiber cable according to claim 1, wherein the plurality of optical fibers includes about 8000 optical fibers.

11. The optical fiber cable according to claim 1, wherein the cladding is configured to confine light within the fiber core.

12. The optical fiber cable according to claim 11, wherein the cladding is formed of a fluoride glass material having a refractive index lower than that of the fiber core.

13. The optical fiber cable according to claim 1, wherein each optical fiber is improved using an annealing method configured to reduce the number of defects in the fiber core.

14. The annealing method is ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ heating the optical fiber to a first temperature higher than the crystallization temperature (T x ) of the optical fiber and lower than the melting temperature (T m ) of the optical fiber; Moving the optical fiber from a first position to a second position at a first acceleration while the optical fiber is at the first temperature; cooling the optical fiber at a critical cooling rate associated with the optical fiber to a second temperature that is lower than the crystallization temperature of the optical fiber and higher than the glass transition temperature (T g ); The optical fiber cable according to claim 13, comprising:

15. The first acceleration is the acceleration due to gravity, The optical fiber cable according to claim 14.

16. The glass transition temperature is about 260 ° C, the crystallization temperature is about 352 ° C, and the melting temperature is about 450 ° C, The optical fiber cable according to claim 14.

17. A system for removing defects in a fixed-length optical fiber including a fiber core and a cladding surrounding the fiber core, An annealing unit including a heating chamber configured to internally heat a given segment of the optical fiber to a first temperature higher than the crystallization temperature (T x ) of the optical fiber and lower than the melting temperature (T m ) of the optical fiber. A heating chamber configured to move the annealing unit from a high position to a low position using free fall motion and further configured to maintain the first temperature of a segment of the optical fiber during a first period of the free fall motion; Comprising: The annealing unit is configured to cool, during a second period, a segment of the optical fiber at a critical cooling rate associated with the optical fiber to a second temperature that is lower than the crystallization temperature (T x ),) of the optical fiber and higher than the glass transition temperature (T g ), After the end of the second period, the annealing unit is further configured to transfer a subsequent segment of the optical fiber into the heating chamber, and the housing is further configured to move the annealing unit from the low position to the high position. System.

18. The annealing unit further includes a first spool configured to supply the optical fiber into the heating chamber and a second spool configured to receive the optical fiber exiting the heating chamber. The system according to claim 17.

19. The annealing unit further includes one or more processors configured to rotate the second spool in a first direction to pull a given segment out of the chamber and draw a subsequent segment into the chamber. The system according to claim 18.

20. The second period starts after the end of the first period during the free fall motion. The system according to claim 19.

21. The one or more processors are: Determining whether a given segment of the optical fiber meets a fiber loss threshold after cooling, If the threshold is not met, rotating the second spool in a second direction opposite to the first direction to return the given segment to the heating chamber for further heating. The system according to claim 19, further configured as such.

22. The optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN). The system according to claim 17.

23. Each segment of the optical fiber has a substantially uniform length of at least about 10 meters, the distance between the high point and the low point is at least about 44 meters, and the free fall motion continues for about 3 seconds. The system according to claim 17.

24. The critical cooling rate is about 40 degrees Celsius (°C) per second. The system according to claim 17.

25. The glass transition temperature is about 260 °C, the crystallization temperature is about 352 °C, and the melting temperature is about 450 °C. The system according to claim 17.

26. A method for removing defects from a fixed-length optical fiber including a fiber core and a cladding surrounding the fiber core, at least partially disposed within an annealing unit of a system including one or more processors, comprising: (a) using the one or more processors to place a given segment of the optical fiber within a heating chamber of the annealing unit; (b) Using the heating chamber and the one or more processors, heating the given segment to a first temperature that is higher than the crystallization temperature (T x ) of the optical fiber and lower than the melting temperature (T m ) of the optical fiber; (c) using the one or more processors to move the annealing unit from a high location to a low location using free fall motion; (d) during the free fall motion, using the heating chamber and the one or more processors to maintain the given segment at the first temperature for a first period; (e) During the second period, using the one or more processors, cooling the given segment at a critical cooling rate of the optical fiber to a second temperature that is lower than the crystallization temperature (T x ) and higher than the glass transition temperature (T g ) of the optical fiber; (f) after the second period, using the one or more processors to move the annealing unit from the low location to the high location; (g) using the one or more processors to repeat steps (a) - (f) for each subsequent segment of the optical fiber until the entire length of the optical fiber has been processed. A method comprising the above steps.

27. The step of cooling the given segment includes pulling the first segment out of the heating chamber at a rate selected based on the critical cooling rate, and the given segment of the optical fiber cools to the second temperature when it exits the heating chamber. The method according to claim 26.

28. When the given segment is pulled out, a subsequent segment of the optical fiber is drawn into the heating chamber. The method according to claim 27.

29. Before step (g), using the one or more processors, determining whether a given segment of the optical fiber meets a fiber loss threshold; if the threshold is not met, using the one or more processors to rotate the second spool in a second direction opposite to the first direction to return the given segment to the heating chamber for further heating; The method according to claim 26, further comprising.

30. The method according to claim 29, further comprising repeating steps (b) to (f) for the given segment to perform the further heating. The method according to claim 29.

31. The second period starts after the end of the first period during the free fall motion. The method according to claim 26.

32. Each segment of the optical fiber has a substantially uniform length of at least about 10 meters, the distance from the high location to the low location is at least about 44 meters, and the free fall motion continues for about 3 seconds. The method according to claim 26.

33. The optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN). The method according to claim 26.

34. The critical cooling rate is at least about 40 degrees Celsius (°C) per second. The method according to claim 26.

35. The glass transition temperature is about 260 °C, the crystallization temperature is about 352 °C, and the melting temperature is about 450 °C. The method according to claim 26.

36. A system for reducing defects in a fixed-length optical fiber including a fiber core and a cladding surrounding the fiber core, A heating element configured to selectively heat a given segment of the optical fiber to a first temperature higher than the crystallization temperature (T x ),) of the optical fiber and lower than the melting temperature (T m ) of the optical fiber, and a clamping system configured to selectively fix the given segment adjacent to the heating element, and an annealing unit including the clamping system. an acceleration chamber configured to accommodate the annealing unit and move a given segment of the optical fiber fixed within the annealing unit from a first position to a second position with a first acceleration and move the annealing unit and the given segment from the second position to the first position with a second acceleration lower than the first acceleration; comprising a given segment of the optical fiber is heated to the first temperature for a first period by the heating element while at the first acceleration; The given segment is cooled over a second period to a second temperature that is lower than the crystallization temperature of the optical fiber and higher than the glass transition temperature (T g ), at a critical cooling rate associated with the optical fiber, The clamping system is configured to release a given segment of the optical fiber after the second period and fix a subsequent segment of the optical fiber adjacent to the heating element. System.

37. A first spool configured to supply the optical fiber into the acceleration chamber, and a second spool configured to receive the optical fiber exiting the acceleration chamber. The system according to claim 36.

38. The acceleration chamber includes one or more processors configured to control the movement of the annealing unit between the first position and the second position and to control the operation of the clamping system and the heating system included in the clamping system. The system according to claim 37.

39. The one or more processors Determine whether a given segment of the optical fiber meets a fiber loss threshold before releasing the given segment. If the threshold is not met, repeatedly move the annealing unit from the first position to the second position at the first acceleration while heating the given segment to the first temperature. The system according to claim 38, further configured as described above.

40. The annealing unit includes a plurality of openings extending along the length of the annealing unit and configured to allow an air flow that cools the given segment during the second period to pass through the unit. The system according to claim 36.

41. The heating element is a coil disposed at the center of the annealing unit, and the optical fiber passes through the center of the coil. The system according to claim 36.

42. The clamping system includes two actuators disposed adjacent to both sides of the heating element and configured to move between a first position where a given segment of the optical fiber is fixed adjacent to the heating element and a second position where the segment is released. Each actuator terminates at a gripping portion configured to compress the optical fiber when the clamping system is in the first position. The system according to claim 41.

43. The second period starts after the end of the first period while at the first acceleration. The system according to claim 36.

44. The optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN). The system according to claim 36.

45. Each segment of the optical fiber has a substantially uniform length of about 3 inches. The system according to claim 36.

46. The distance between the first position and the second position is at least about 0.5 meters, and the annealing unit moves from the first position to the second position in about 320 milliseconds at the first acceleration. The system according to claim 36.

47. The critical cooling rate is at least about 40 degrees Celsius (°C) per second. The system according to claim 36.

48. The glass transition temperature is about 260 °C, the crystallization temperature is about 352 °C, and the melting temperature is about 450 °C. The system according to claim 36.

49. A method for removing defects from a fixed-length optical fiber including a fiber core and a cladding surrounding the fiber core, at least partially disposed within an annealing unit of a system including one or more processors, comprising: (a) using the one or more processors to fix a given segment of the optical fiber adjacent to a heating element of the annealing unit; (b) Using the one or more processors and the heating element, heating the given segment to a first temperature that is higher than the crystallization temperature (T x ) of the optical fiber and lower than the melting temperature (T m ) of the optical fiber; (c) using the one or more processors to move the annealing unit from a first position to a second position at a first acceleration; (d) using the one or more processors and the heating element to maintain the first temperature of the given segment over a first period during the acceleration; (e) During the second period, using the one or more processors, cooling the given segment at a critical cooling rate of the optical fiber to a second temperature that is lower than the crystallization temperature and higher than the glass transition temperature (T g ) of the optical fiber; (f) after the second period, using the one or more processors to release the given fiber segment; (g) using the one or more processors to move the annealing unit from the second position to the first position at a second acceleration slower than the first acceleration; (h) using the one or more processors to repeat steps (a) to (g) for each subsequent segment of the optical fiber until the entire length of the optical fiber has been processed. A method comprising.

50. Before step (f), using the one or more processors to determine whether a given segment of the optical fiber meets a fiber loss threshold; If the threshold is not met, using the one or more processors to repeat steps (b) to (e) for the given segment. The method according to claim 49, further comprising.

51. Step (a) includes fixing the given segment to the clamping system of the annealing unit, and step (f) includes releasing the given segment from the clamping system. The method according to claim 49.

52. The second period starts after the end of the first period while being the first acceleration. The method according to claim 49.

53. Each segment of the optical fiber has a substantially uniform length of about 3 inches. The method according to claim 49.

54. The distance between the first position and the second position is at least about 0.5 meters, and the annealing unit moves from the first position to the second position in about 320 milliseconds while being the first acceleration. The method according to claim 49.

55. The optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN). The method according to claim 49.

56. The critical cooling rate is at least about 40 degrees Celsius (°C) per second. The method according to claim 49.

57. The glass transition temperature is about 260 °C, the crystallization temperature is about 352 °C, and the melting temperature is about 450 °C. The method according to claim 49.

58. An optical fiber power supply system, comprising: A laser light source configured to emit high-power laser energy; A photodetector configured to convert detected light into electrical energy; An optical fiber cable; The optical fiber cable includes: A first end coupled to the laser light source; An opposite second end coupled to the photodetector; A length extending between the first end and the second end; A plurality of optical fibers; Each of the optical fibers extends along the length of the cable and has a thermal filler surrounding the optical fiber. An optical fiber power supply system.

59. The laser light source includes one or more laser diode bars operating at a wavelength of about 2.1 μm. The optical fiber power supply system according to claim 58.

60. The photodetector includes at least one photodiode detector. The optical fiber power supply system according to claim 58.

61. The optical fiber power supply system according to claim 58. Each optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN).

62. The optical fiber cable can transmit laser energy having a power of about 1 gigawatt over a distance of about 1000 kilometers (km) with a loss of about 0.1 decibel (dB). ​ The optical fiber power supply system according to claim 58.

63. An optical transmitter configured to be coupled to the second end of the optical fiber cable and transmit a data signal; An optical receiver configured to be coupled to the first end of the optical fiber cable and receive the data signal; The optical fiber power supply system according to claim 58, further comprising:

64. The photodetector is configured to supply the electrical energy to an electrical load, and the data signal includes information regarding power requirements of the electrical load. The optical fiber power supply system according to claim 63.

65. Further comprising a power control unit configured to control the amount of power supplied by the laser light source based on the data signal. The optical fiber power supply system according to claim 64.

66. The power control unit is configured to turn off the laser light source when the power requirement exceeds a threshold amount of power. The optical fiber power supply system according to claim 65.

67. The power control unit is configured to determine the number of the plurality of optical fibers required to meet the power requirement and supply laser energy from the laser light source to the photodetector using the number of optical fibers. The optical fiber power supply system according to claim 65.

68. The power control unit is coupled to an external power source configured to supply power to the laser light source. The optical fiber power supply system according to claim 65.

69. A method for managing power supply in an optical fiber power supply system comprising a transmission unit having a laser light source, a reception unit having a photodetector, and an optical fiber cable coupled between the transmission unit and the reception unit, wherein the optical fiber cable includes a plurality of optical fibers, each optical fiber extending along the length of the optical fiber cable, the method comprising: Transmitting high-power laser energy from the transmission unit to the reception unit using a certain number of the optical fibers included in the optical fiber cable; Receiving, in a processor, a data signal transmitted from the reception unit to the transmission unit using the optical fiber cable and including information regarding power requirements of an electrical load coupled to the reception unit; Controlling the high-power laser energy output by the transmission unit by using the processor to adjust the number of the optical fibers used to transmit the laser energy based on the power requirement of the electrical load; A method including the above.

70. The step of controlling the high-power laser energy output by the transmission unit further includes the step of interrupting the transmission of the high-power laser energy when the power requirement of the electrical load exceeds a threshold amount of power related to an external power source coupled to the transmission unit. The method according to claim 69.

71. The step of controlling the high-power laser energy output by the transmission unit further includes the step of adjusting the amount of power output by the laser light source according to the power requirement of the electrical load. The method according to claim 69.

72. The data signal further includes information for verifying the power supply to the electrical load. The method according to claim 69.

73. The data signal is an optical data signal generated by an optical transmitter included in the receiving unit and transmitted via the optical fiber cable. The step of receiving the data signal includes receiving the optical data signal by an optical receiver included in the transmission unit. The method further includes the step of converting the optical data signal into a digital data signal. The method according to claim 69.

74. Each optical fiber is surrounded by a thermal filler. The method according to claim 69.

75. The optical detector includes at least one photodiode detector. The method according to claim 69.

76. The optical fiber cable can transmit laser energy having a power of about 1 gigawatt over a distance of about 1000 kilometers (km) with a loss of about 0.1 decibel (dB). The method according to claim 69.

77. The laser light source includes one or more laser diode bars operating at a wavelength of about 2.1 μm. The method according to claim 69.

78. Each optical fiber contains ZrF 4 -BaF 2 -LaF 3 -AlF 3 -NaF (ZBLAN). The method according to claim 69.

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