Fiber Internal Retroreflector

Abstract

An optical fiber may include: a core, wherein core-guided light generated by one or more light sources propagates along the length of at least one optical fiber; one or more claddings surrounding the core to guide the cladding-guided light generated by the one or more light sources along the length of at least one optical fiber; and a reflector structure machined into the at least one optical fiber. The reflector structure may include a plurality of angled facets arranged at one or more respective angles relative to an axis of the optical fiber to reflect at least a portion of the core-guided light and / or the cladding-guided light passing through the optical fiber.

Description

Technical Field

[0001] The present invention generally relates to a reflector structure in an optical fiber, and more particularly, to a reflector structure fabricated in an optical fiber to reflect at least a portion of cladding-guided light and / or core-guided light passing through the optical fiber. Background Art

[0002] Optical pumping refers to the process of injecting pump light into a gain medium in order to excite the gain medium and / or some of the constituent electrons of the gain medium to other (e.g., higher) energy levels. In the case of a laser or laser amplifier, the goal of optical pumping is to achieve a population inversion in the gain medium, thereby obtaining light amplification by stimulated emission in a specific range of optical wavelengths (e.g., a specific gain bandwidth). In particular, when the population of an excited state exceeds the population of a ground state or a lower excited state, a population inversion is achieved, and the medium can act as a laser or optical amplifier. For example, in a multi-clad optical fiber (e.g., a double-clad optical fiber, a triple-clad optical fiber, and / or the like), laser light propagates in a core doped with rare earth ions, and the core is surrounded by an inner cladding in which the pump light propagates. The pump light is typically confined to the inner cladding by an outer cladding having a lower refractive index, and the pump light may also partially propagate in the core, where the pump light may be absorbed by the laser-active ions. Thus, the inner cladding guides the pump light to be absorbed in the doped core for laser amplification along the entire length of the optical fiber. Summary of the invention

[0003] According to some embodiments, an optical component may include: one or more light sources; and at least one optical fiber, comprising: a core, wherein core-guided light generated by the one or more light sources propagates along the length of the at least one optical fiber; one or more claddings surrounding the core to guide the cladding-guided light generated by the one or more light sources along the length of the at least one optical fiber; and a reflector structure machined into the at least one optical fiber, wherein the reflector structure includes a plurality of angled facets arranged at one or more corresponding angles relative to an axis of the at least one optical fiber to reflect at least a portion of the one or more core-guided lights or cladding-guided lights passing through the at least one optical fiber.

[0004] According to some embodiments, a reflector structure may include: a plurality of angled facets machined into an end of a multi-clad optical fiber, wherein the plurality of angled facets are arranged at an angle in a range of 30° to 40° relative to an axis of the multi-clad optical fiber to reflect at least a portion of the core-guided light or the cladding-guided light after a first pass through the multi-clad optical fiber; and a central pass-through port formed at a junction of the plurality of angled facets for transmitting at least a portion of the core-guided light into the core of the multi-clad optical fiber after a first pass and one or more subsequent passes through the multi-clad optical fiber.

[0005] According to some embodiments, a method may include machining a plurality of angled facets in an end of a multi-clad optical fiber, wherein the plurality of angled facets are machined such that the plurality of angled facets are formed at respective angles in a range of 30° to 40° relative to an axis of the multi-clad optical fiber; and heating surfaces of the plurality of angled facets to a temperature at which the surfaces of the plurality of angled facets reflow and become smooth via surface tension. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A-Figure 1C is a schematic diagram of one or more example embodiments of a reflector structure machined into an optical fiber.

[0007] Figure 2 is an example graph showing the retroreflection efficiency as a function of input light divergence for a reflector structure machined into an optical fiber.

[0008] Figure 3 is an example graph showing the absorbed pump power distribution for single-pass and double-pass pumping in an optical fiber.

[0009] Figure 4 is an example graph showing the power in a beam retroreflected by a reflector structure machined into an optical fiber as a function of divergence angle.

[0010] Figure 5 is a flow chart of an example process for manufacturing an optical assembly that includes a reflector structure machined into an optical fiber. DETAILED DESCRIPTION

[0011] The following detailed description of exemplary embodiments refers to the accompanying drawings.The same reference numbers in different drawings may identify the same or similar elements.

[0012] Fiber lasers are a class of lasers that have significant advantages over other types of lasers, such as free-space lasers, including efficiency and practicality. With the advent of multi-clad optical fibers (e.g., double-clad optical fibers, triple-clad optical fibers, and / or the like), fiber lasers have been scaled to kilowatt (kW) power levels. In multi-clad optical fibers, pump light propagates in a relatively large inner cladding, which is typically 125 to 600 microns in diameter, and laser light propagates in a much smaller core, which is typically 5 to 100 microns in diameter. The core is typically doped with rare earth ions, such as ytterbium, and is surrounded by an inner cladding that guides the pump light to be absorbed in the doped core for laser amplification along the entire length of the fiber. Ideally, at the output of the laser, no light propagates in the inner cladding, and all of the output laser beam comes from the core. In some fiber laser systems, it may also be desirable to exclusively propagate core light between components or between amplification stages.

[0013] In practice, however, the output of a fiber laser or amplifier based on a multi-clad fiber typically includes some core-guided light and some cladding-guided light. The cladding-guided light may include residual unabsorbed pump light, laser light that escapes from the core into the cladding (e.g., due to splicing losses, scattering, or spontaneous emission in the core), and / or the like. The cladding-guided light may include beams of a wide range of divergence angles and various wavelengths, depending on their source and the configuration of the laser system. In various applications, the cladding-guided light may be harmful, and is therefore typically removed or "stripped" from the fiber using a cladding-light stripper after a single pass through one or more active fibers. However, safely and effectively removing the cladding light is a significant technical challenge. For example, the stripped cladding-guided light is typically converted into heat, and care must be taken to avoid overheating the fiber coating or other components such as ferrules, splice protectors, and / or the like. Furthermore, removing the cladding guided light after a single pass through one or more optical fibers may reduce pump efficiency because the remaining unabsorbed pump light is essentially discarded after the first pass.

[0014] Some embodiments described herein relate to in-fiber retroreflectors that can be micromachined into an optical fiber to serve as a total-internal reflection (TIR) ​​structure that is arranged to reflect light propagating in the optical fiber. In some embodiments, the in-fiber retroreflector can be used with a double-clad active fiber, a triple-clad active fiber, a multi-clad active fiber, and / or the like to allow pump power propagating in a pump guide layer (e.g., cladding) to pass through twice, while the signal core (with a thinner cladding) extends outside the in-fiber retroreflector and allows the signal to be transmitted without retroreflection. In this way, the in-fiber retroreflector can mitigate the potential harmful effects of cladding-guided light, which may include laser light and / or residual unabsorbed pump light that escapes from the core into the cladding, by preventing the cladding-guided light from accompanying the amplified signal light and / or reaching the signal source. Furthermore, in contrast to a cladding light stripper that typically removes unabsorbed pump light after the pump light passes through one or more active optical fibers, the intra-fiber retroreflector described herein does not remove unabsorbed pump light, but instead causes the unabsorbed pump light to retroreflect. In this way, the (unabsorbed) retroreflected pump light has another opportunity to be absorbed by the fiber core, thereby improving performance.

[0015] Figure 1A-Figure 1C1 is a schematic diagram of one or more example embodiments 100 of an intra-fiber reflector structure 110 fabricated into an optical fiber. For example, as described herein, the intra-fiber reflector structure 110 has a plurality of planar or nearly planar facets 112 that are arranged to reflect cladding guided light and / or at least a portion of core guided light passing through the optical fiber. In general, Figure 1A A perspective view of a reflector structure 110 is shown in a design having three facets and no output port. Figure 1B-Figure 1C A side view of a reflector structure 110 is shown in a design where the reflector structure 100 has a central pass-through port.

[0016] Thus, as described herein, a reflector structure 110 can be machined into an optical fiber that is arranged to receive input light 120 generated by one or more light sources. For example, in some embodiments, the optical fiber can include: a core in which core-guided light (e.g., signal light and / or the like) generated by the one or more light sources propagates along the length of the optical fiber; and one or more claddings that surround the core to guide the cladding-guided light (e.g., pump light) generated by the one or more light sources along the length of the optical fiber. In addition, the reflector structure 110 can be machined into the optical fiber and have a plurality of angled facets 112 that are arranged at one or more corresponding angles relative to the axis of the optical fiber to reflect the cladding-guided light and / or at least a portion of the core-guided light passing through the optical fiber. Thus, as described in further detail herein, the reflector structure 110 can be a TIR structure micromachined into an optical fiber (e.g., a double-clad fiber, a triple-clad fiber, a multi-clad fiber, and / or the like) to act as a reflector for light propagating in the optical fiber such that pump power propagating in a pump guide layer (e.g., one or more claddings surrounding the core) passes through twice, while the signal guide core (having a thinner cladding) extends beyond the reflector structure 110 and allows the signal carried in the core to be transmitted without back reflection. Additionally or alternatively, in some embodiments, the plurality of facets 112 of the reflector structure 110 can have a dichroic coating to reflect or back reflect wavelengths in a particular range (e.g., pump light or cladding-guided light) and transmit or eliminate wavelengths in another range (e.g., signal light or core-guided light that may be trapped in a pump guide layer instead of the signal core).

[0017] For example, Figure 1AAs shown in FIG. 1 , the end of a circular optical fiber can be micromachined to form a reflector structure 110 having three (3) facets 112-1, 112-2, 112-3 that are tilted at respective angles relative to the axis of the optical fiber. For example, in some embodiments, the facets 112-1, 112-2, 112-3 can be tilted at an angle in the range of 30° to 40°. In some embodiments, the three facets 112-1, 112-2, 112-3 can be perpendicular to each other and can be at a sinusoidal angle. -1 = (1 / √3)≈35.3°. In other words, the three facets 112-1, 112-2, 112-3 may be arranged at an angle θ relative to the axis of the optical fiber such that sinθ=1 / √3, whereby the three angled facets 112-1, 112-2, 112-3 are mutually orthogonal and form a corner-cube retroreflector with TIR. Thus, in a silica glass fiber in the wavelength range of 1 μm to 2 μm, where the refractive index near 1 μm is about 1.45, the minimum TIR angle is sinθ. -1 (1 / 1.45)≈43.6°. In this regard, the TIR margin is 90°-35.3°-43.6°=11.1°, meaning that light in the fiber at an angle less than 11.1° relative to the fiber axis can be retroreflected by TIR, or equivalently, the reflector structure 110 can retroreflect light with a numerical aperture (NA) of up to 0.28. Additionally or alternatively, the reflector structure 110 can include two facets 112, four facets 112, or more than four facets 112, in which case the angular acceptance for TIR can be reduced relative to the angular acceptance for TIR that is favorable provided by a corner cube retroreflector having three mutually orthogonal facets. Therefore, in designs where the reflector structure 110 has two facets 112, four facets 112, or more than four facets 112, a thin film reflective coating can be applied to the facets 112 to increase the reflectivity of the facets 112. Furthermore, in some embodiments, the plurality of facets 112 can have equal sizes, different sizes, equal angles relative to the optical fiber axis, and / or different angles relative to the optical fiber axis.

[0018] Usually, if Figure 1A The reflector structure 110 shown will reflect most of the light transmitted in the optical fiber (except for light emitted at the periphery of the optical fiber which may not be fully reflected). Figure 1A In the design shown, the reflector structure 110 has no output port. Figure 1BAn example fiber internal reflector structure 110 is shown, which includes a central pass-through port 114, wherein an input fiber segment 140 can be a double-clad fiber, a triple-clad fiber, a multi-clad fiber, and / or the like coupled to one or more light sources. For example, the one or more light sources can be arranged to transmit cladding-guided light to be retroreflected (e.g., pump light that has made a single pass through the active fiber), transmit core-guided light (e.g., signal light) to be transmitted in the central core 130, which is continuous and extends beyond the fiber internal reflector structure 110 and into the downstream portion 150 of the optical fiber, and / or the like. For example, as Figure 1B As shown, an extended length of the optical fiber has been machined away, leaving a thin through-port portion 130 that includes a central core that carries the signal from left to right, and a multi-faceted reflector structure 110 on the left half of the optical fiber 140. Cladding-guided light traveling through the optical fiber can enter the incident fiber portion 140 from the left, and can be reflected back to the left after being reflected by the multiple facets 112. Cladding-guided light located in the middle of the incident fiber segment 140 may not be reflected back by the reflector structure 110, and may pass through the central through-port 114, which may have a diameter as small as possible to improve the reflection efficiency. For example, in some embodiments, the central through-port 114 may have a diameter in the range of 50 microns to 100 microns. In some embodiments, the core-guided light can propagate from left to right or from right to left. In Figure 1B to the right, or with a step (e.g. Figure 1B As shown), or by tapering, the downstream fiber section 150 can be restored to its original size. Additionally or alternatively, another fiber internal reflector structure can be provided on the downstream fiber section 150, in which case, Figure 1B The optical assembly shown may be retroreflective in both directions. Alternatively, in some embodiments, the thinned through fiber may have no substantial middle portion. For example, Figure 1C An example of an intra-fiber reflector structure 110 is shown where the optical fiber may transition back to full size immediately following the faceted reflector structure 110 without thinning through a substantially mid-portion of the optical fiber.

[0019] In some embodiments, Figures 1A to 1CThe reflector structure 110 shown can be processed into an active optical fiber coupled to one or more light sources. For example, in some embodiments, the active optical fiber can include an optical fiber capable of producing laser amplification, such as a rare earth doped optical fiber, a bismuth doped optical fiber, a Raman gain optical fiber, and / or the like. However, in the case where the reflector structure 110 is processed into an active optical fiber, there may be additional heating and / or stress due to absorption of cladding guided (e.g., pump) light near the reflector structure 110 processed into the active optical fiber. Therefore, in some embodiments, an optical component incorporating the reflector structure 110 can include an active optical fiber coupled to one or more light sources, and a matching (or nearly matching) passive optical fiber spliced ​​downstream (e.g., adjacent) to the active optical fiber. In this case, the reflector structure 110 can be processed into the passive optical fiber, which can reduce or eliminate heating and / or stress caused by absorption of cladding guided light.

[0020] In some embodiments, as described herein, the reflector structure 110 can be processed into any suitable optical fiber, the optical fiber comprising: a core, wherein core-guided light generated by one or more light sources propagates along the length of the optical fiber; and one or more claddings surrounding the core to guide cladding-guided light generated by the one or more light sources along the length of at least one optical fiber. For example, in some embodiments, the optical fiber can be a double-clad optical fiber, a triple-clad optical fiber, a multi-clad optical fiber, and / or the like. In some embodiments, where the reflector structure 110 is processed into an optical fiber having a triple-clad or multi-clad structure (e.g., where the reflector structure 110 is processed into an optical fiber having more than one pump-guide layer or cladding-guide layer), the back-coupling efficiency can be improved. For example, if the incident cladding-guided light and / or core-guided light is substantially confined within a first pump-guided layer or cladding-guided layer (e.g., an inner cladding), some back-reflected power that may escape from the optical fiber can be captured by a second pump-guided layer or cladding-guided layer (e.g., an outer cladding).

[0021] As mentioned above, Figure 1A-Figure 1C is one or more examples provided. Other examples may vary Figure 1A-Figure 1C For example, as one or more examples provided Figure 1A-Figure 1C The number and arrangement of the components shown in FIG. Figure 1A-Figure 1C The arrangements shown may include additional components, fewer components, different components, or components that are different from the Figure 1A-Figure 1C Components with different arrangements of components shown. Additionally or alternatively, Figure 1A-Figure 1C A set of components (e.g., one or more components) in a can perform a process described as being Figure 1A-Figure 1C One or more functions performed by another group of components in a

[0022] Figure 2is an example graph 200 showing a reflector structure (e.g., as Figures 1A-1C , and described in further detail above), as a function of the input light divergence. For example, Figure 2 The example graph 200 shown is based on ray tracing calculations that indicate the portion of light that is reflected back by the reflector structure 110 in various situations. Figure 2 In the embodiment of the present invention, a first intra-fiber reverse reflector is used in a 500 micron diameter silica optical fiber without an output port (e.g., Figure 1A ), curve 210 shows the retroreflection efficiency as a function of the input light divergence expressed in radians (roughly equivalent to the numerical aperture (NA)). In addition, for a second in-fiber retroreflector used in a 500 μm diameter silica fiber with a 100 μm diameter through hole (e.g., as shown in FIG. Figure 1B-Figure 1C ), curve 220 shows the retroreflection efficiency as a function of the input light divergence expressed in radians. Figure 2 The illustrated example graph 200 shows that the reflector structure does not reflect back some of the light passing through the fiber. For example, in the case of a silica fiber with no output (e.g., curve 210), the losses may include a portion of the cladding-guided light near the edge of the fiber that is not fully reflected back, and in the case of a silica fiber with a 100 micron output via (e.g., curve 220), there is some additional loss of cladding-guided light entering the center through port 114. Nonetheless, as Figure 2 As shown, even at divergence angles as high as 0.25 radians, the reflection efficiency is relatively high (e.g., over about 65% for a reflector structure 110 having a 100 micron diameter through hole, or over about 70% for a reflector structure 110 without an output port). In addition, minimizing the diameter of the center through port 114 (e.g., using a 50 micron diameter center through port 114), rather than using a 100 micron diameter as in the case of curve 220, will make curve 220 closer to the "no output" case (curve 210) because there will be less loss due to the cladding guiding the light into the center through port 114.

[0023] As mentioned above, Figure 2 are provided as examples. Other examples may differ from the Figure 2 Description.

[0024] Figure 3 is an example graph 300 showing absorbed pump power distributions for single-pass and double-pass pumping in an optical fiber.

[0025] More specifically, an important application of the intra-fiber reflector structures (one or more) described herein is to reduce the length of the active fiber in a fiber laser in order to minimize fiber cost, maximize laser emission efficiency, reduce nonlinear effects, such as stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), which would otherwise limit the operating power, and / or the like. In many fiber lasers, the required fiber length can be determined based on the rate at which pump power is absorbed into the core. Therefore, by enabling the cladding guided light (e.g., pump light) to pass twice, the intra-fiber reflector structures (one or more) described herein can reduce the required fiber length and / or increase the absorption efficiency for a given fiber length. In addition, in some embodiments, the intra-fiber reflector structures (one or more) described herein minimize the variation in the pump power absorbed along the active fiber, so that the fiber is more uniformly pumped. At power levels of several kilowatts, an important factor is to distribute the absorbed power well to avoid excessive thermal loads in certain areas of the fiber while other areas are underutilized. This effect is Figure 3 3, which shows the absorbed pump power load as a function of position along the active fiber. Figure 3 , curve 310 represents the case of conventional single-pass pumping (e.g., where a cladding light stripper is used to remove the cladding guided light after a single pass through the optical fiber), and curve 320 represents the idealized case of two-pass pumping, where the intra-fiber reflector structure(s) described herein are capable of achieving 100% retroreflection.

[0026] exist Figure 3 In the illustrated example graph 300, the length of the single pass structure shown by curve 310 is normalized to a length of one (1), with 90% absorption (10 dB), and the absorbed pump power is normalized to one (1) when single pass pumping is enabled. The double pass structure shown by curve 320 is designed to achieve the same 10 dB absorption using the same fiber, thus using only half the fiber of the single pass structure. Figure 3 As shown, the absorbed power in the single pass configuration varies from 1 down to 0.1 by curve 310, while the absorbed power in the double pass pump configuration varies from 1.1 (1 forward pump plus 0.1 reverse reflected pump) down to 0.63 by curve 320. This calculation shows that the uniformity of the absorbed pump is significantly improved while achieving the same total pump absorption, and significant fiber length savings are achieved.

[0027] As mentioned above, Figure 3are provided as examples. Other examples may differ from the Figure 3 Description.

[0028] Figure 4 is an example graph 400 showing the power in a beam retroreflected by a reflector structure machined into an optical fiber as a function of divergence angle.

[0029] More specifically, in Figure 4 , curve 410 represents the case of a reflector structure having three (3) facets arranged at an angle θ relative to the fiber axis such that θ=1 / √3 (e.g., θ≈35.3°). In this case, the three facets of the reflector structure can be orthogonal to each other and can form a corner cube retroreflector with TIR, as described above. In this case, excluding a small portion of cladding guided light that leaks from the periphery of the fiber, substantially all of the light captured by the reflector structure is reflected back in the opposite direction to pass through the fiber a second time. In this way, there is substantially no loss in brightness of the light reflected back. In other words, if the light captured by the reflector structure enters at a certain angle, the corner cube retroreflector design will cause the light to be reflected back at the same angle.

[0030] Thus, curve 410 shows an optimal (eg, lowest possible) divergence angle, but the total reflected power is limited to approximately 82%, so that approximately 18% of the incident light is lost after the first pass through the optical fiber. Figure 4 As further shown, curve 420 illustrates the case of a reflector structure in which three (3) facets are offset downwardly by 1.5° from the corner cube design, such that θ≈35.3°-1.5°≈33.8°. In this case, the total reflected power can be increased from about 82% to about 88% at the expense of an increase in the divergence angle of the reflected light from about 0.25 radians to about 0.4 radians. In other words, adjusting the angle of the facets relative to the fiber axis can allow the reflector structure to capture more light than the corner cube design, but at the expense of curve 420 being offset to the right relative to curve 410, meaning that the light reflected back has a higher divergence angle. Thus, the angles of the facets of the reflector structure can be adjusted so that the tradeoff between a perfect corner cube design with minimal divergence angle and other angles that can capture more light without increasing the divergence angle beyond an acceptable range can be balanced (e.g., the divergence angle should not be so high that some of the reflected light cannot be guided by the double cladding refractive index layer).

[0031] As mentioned above, Figure 4 are provided as examples. Other examples may differ from the Figure 4 Description.

[0032] Figure 5is a flow chart of an example process 500 for manufacturing an optical assembly that includes a reflector structure machined into an optical fiber.

[0033] like Figure 5 As shown, process 500 may include machining a plurality of angled facets in an end of a multi-clad optical fiber, wherein the plurality of angled facets are machined so as to form the plurality of angled facets at respective angles in a range of 30° to 40° relative to an axis of the multi-clad optical fiber (block 510).

[0034] For example, in some embodiments, a short pulse laser (e.g., a nanosecond laser, a picosecond laser, a femtosecond laser, and / or the like) can be used to machine a plurality of angled facets into the end of a multi-clad optical fiber. Additionally or alternatively, a carbon dioxide (CO2) laser can be used to machine a plurality of angled facets into the end of a multi-clad optical fiber. Furthermore, in some embodiments, a short pulse or CO2 laser used to machine a plurality of angled facets into the end of a multi-clad optical fiber can be operated in a tangential machining mode so as to carve a plurality of angled facets with the edge of the beam. Additionally or alternatively, the angled facets can be machined into the end of a multi-clad optical fiber using non-laser machining processes, such as precision filing, grinding, polishing, water jet machining using diamond grit, wet or dry etching, and / or the like. Generally, after the facets are machined into the end of the multi-clad optical fiber, the facets can have a slightly rough surface. However, the faceted surface is generally required to have a shiny or glossy surface in order to retroreflect the cladding-guided light and / or the core-guided light of the multi-clad optical fiber.

[0035] Therefore, if Figure 5 As further shown, process 500 may further include heating the surfaces of the plurality of angled facets to a temperature at which the surfaces of the plurality of angled facets re-flow and become smooth via surface tension (block 520). For example, in some embodiments, the surfaces of the plurality of angled facets may be heated (e.g., fire polishing) using a flame torch, an arc, a filament, a CO2 laser, and / or the like. Additionally or alternatively, other techniques, such as wet or dry etching, may be used to smooth the surfaces of the angled facets. In some embodiments, after the smoothing process, the surfaces of the facets may be slightly rounded or deformed, but the rounding or deformation does not significantly degrade the performance of the reflector structure. In this manner, the heated (slightly roughened) machined area may load the facet surfaces so that after the surfaces cool and harden, the facet surfaces will have a smooth, shiny, and glossy surface. In this manner, the smooth surfaces of the facets may retroreflect at least a portion of the core-guided light and / or cladding-guided light that was not absorbed after a first pass through the multi-clad optical fiber, so that the retroreflected light may pass through the multi-clad optical fiber a second time.

[0036] Process 500 may include other embodiments, such as any single embodiment or any combination of embodiments described below and / or in combination with one or more other processes and / or embodiments described elsewhere herein.

[0037] For example, after manufacture, the reflector structure can be packaged in a reduced pressure sealed package to avoid cracking, ensure cleanliness, etc. In some embodiments, the downstream portion of the reflector structure can be re-coated with a polymer. In some embodiments, the TIR facets can remain exposed to air to maintain TIR performance. Additionally or alternatively, the TIR facets can be coated with a reflective thin film coating, in which case the TIR facets can be similarly re-coated (e.g., in a polymer).

[0038] Although Figure 5 Example blocks of process 500 are shown. In some embodiments, process 500 may include additional blocks, fewer blocks, different blocks, or different blocks. Figure 5 Additionally or alternatively, two or more blocks of process 500 may be performed in parallel.

[0039] The foregoing disclosure provides illustration and description, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations may be made in light of the above disclosure or may be acquired from practice of the embodiments.

[0040] As used herein, satisfying a threshold may refer to a value greater than a threshold, greater than or equal to a threshold, less than a threshold, less than or equal to a threshold, equal to a threshold, not equal to a threshold, etc., depending on the context.

[0041] Even though particular combinations of features are recited in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the various embodiments. In fact, many of these features may be combined in ways not specifically recited in the claims and / or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of the various embodiments includes the combination of each dependent claim with every other claim in the claim set.

[0042] Unless explicitly stated, the elements, actions or instructions used herein should not be interpreted as key or necessary. In addition, as used herein, the article "one" is intended to include one or more items, and can be used interchangeably with "one or more". In addition, as used herein, the article "the" is intended to include one or more items associated with the article "the", and can be used interchangeably with "one or more". In addition, as used herein, the term "group" is intended to include one or more items (e.g., related items, unrelated items, combinations of related and unrelated items, etc.), and can be used interchangeably with "one or more". Wherein, when only one item is included, the phrase "only one" or similar words are used. In addition, as used herein, the term "having" or its similarity is intended to be used as an open term. In addition, the phrase "based on" is intended to mean "based at least in part", unless otherwise explicitly stated. In addition, as used herein, the term "or" is intended to be included when used in a series of parallels, and can be used interchangeably with "and / or", unless otherwise explicitly stated (e.g., if used in combination with "any" or "only one of them").

[0043] Related Applications

[0044] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 981,872, filed on February 26, 2020, and entitled “IN-FIBERRETROREFLECTOR,” the contents of which are incorporated by reference in their entirety.

Claims

1. An optical component, comprising: one or more light sources; as well as At least one optical fiber, including: a fiber core, wherein the fiber core directs light produced by one or more light sources to propagate along the length of the at least one optical fiber; one or more claddings surrounding the core to guide cladding-guided light generated by one or more light sources along the length of the at least one optical fiber; as well as a reflector structure machined into the at least one optical fiber, wherein the reflector structure includes a plurality of angled facets arranged at one or more corresponding angles relative to an axis of the at least one optical fiber to retroreflect at least a portion of one or more core-guided light or cladding-guided light passing through the at least one optical fiber to allow two passes of the retroreflected light propagating within the one or more claddings, The reflector structure includes a central through port to transmit at least a portion of the core guided light to a downstream portion of the at least one optical fiber.

2. The optical component of claim 1, wherein the plurality of angled facets comprises three angled facets, each angled facet being arranged at an angle in the range of 30° to 40° relative to the axis of the at least one optical fiber.

3. The optical component of claim 2, wherein the angle is an angle θ such that sinθ=1 / √3 and such that the three angled facets are mutually orthogonal.

4. The optical assembly of claim 1 , wherein the at least one optical fiber comprises: an active optical fiber coupled to one or more light sources; and A passive optical fiber is spliced ​​downstream of the active optical fiber, wherein a reflector structure is fabricated into the passive optical fiber.

5. The optical assembly of claim 1, wherein the at least one optical fiber comprises an active optical fiber coupled to the one or more light sources, and wherein the reflector structure is machined into the active optical fiber.

6. The optical component of claim 1, wherein the plurality of angled facets comprises two, four, or more angled facets having a thin film reflective coating.

7. The optical assembly of claim 1, wherein the plurality of angled facets are of equal size and are arranged at equal angles relative to an axis of the at least one optical fiber.

8. The optical assembly according to claim 1, wherein: At least two of the plurality of angled facets have different sizes or are arranged at different angles relative to an axis of the at least one optical fiber.

9. An optical component according to claim 1, wherein the plurality of angled facets include a dichroic coating such that a portion of the core-guided light or cladding-guided light reflected by the reflector structure includes a wavelength within a first range, and such that a second portion of the core-guided light or cladding-guided light including a wavelength within a second range is not reflected.

10. A reflector structure comprising: machining a plurality of angled facets in a distal end of a multi-clad optical fiber, wherein the plurality of angled facets are arranged at an angle in a range of 30° to 40° relative to an axis of the multi-clad optical fiber to retroreflect at least a portion of one or more core-guided lights or cladding-guided lights after a first pass through the multi-clad optical fiber to allow two passes of the retroreflected light propagating within the multi-clad optical fiber; and A center pass-through port is formed at the junction of the plurality of angled facets for transmitting at least a portion of the core-guided light to a downstream portion of the multi-clad optical fiber.

11. The reflector structure of claim 10, wherein the diameter of the central pass-through port is in the range of 50 microns to 100 microns.

12. The reflector structure of claim 10, wherein the downstream portion of the multi-clad optical fiber includes a through portion in which one or more claddings surrounding the core are processed away.

13. The reflector structure of claim 12, wherein the downstream portion of the multi-clad optical fiber reverts to the original size of the multi-clad optical fiber downstream of the passing portion.

14. The reflector structure of claim 10, wherein the angle is sin-1(1 / √3)≈35.3°, such that the plurality of angled facets are mutually orthogonal and the reflector structure forms a corner cube retroreflector with total internal reflection.

15. A method of manufacturing a reflector structure, comprising: machining a plurality of angled facets in a distal end of the multi-clad optical fiber, wherein the plurality of angled facets are machined such that the plurality of angled facets are formed at respective angles in a range of 30° to 40° relative to an axis of the multi-clad optical fiber; in, The plurality of angled facets are arranged to retroreflect at least a portion of one or more core-guided light or cladding-guided light passing through the multi-clad optical fiber so as to allow two passes of the retroreflected light propagating within the multi-clad optical fiber. Wherein, the plurality of angled facets comprise a reflector structure, and at a junction of the plurality of angled facets, the reflector structure comprises a central through port for transmitting at least a portion of the core guided light to a downstream portion of the multi-clad optical fiber.

16. The method of manufacturing a reflector structure according to claim 15, wherein the plurality of angled facets are machined into the end of the multi-clad optical fiber using a short pulse laser or a carbon dioxide laser.

17. The method of manufacturing a reflector structure according to claim 16, wherein the short pulse laser or CO2 laser is operated in a tangential processing mode to carve a plurality of angled facets with the edge of the beam.

18. The method for manufacturing a reflector structure according to claim 15, further comprising: The surface of the plurality of angled facets is caused to reflow and smoothen via surface tension.

19. The method for manufacturing a reflector structure according to claim 15, further comprising: The plurality of angled facets are coated with a reflective thin film coating.

20. The method of fabricating a reflector structure of claim 18, wherein the surfaces of the plurality of angled facets are heated using one or more of a flame torch, an arc, a filament, or a carbon dioxide laser.

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