4368 results about "Single-mode optical fiber" patented technology

A large core photonic crystal fiber for transmitting radiation having a core comprising a substantially transparent core material and having a core diameter of at least 5 mu. The fiber also comprises a cladding region surrounding the length of core material, wherein the cladding region comprises a first substantially transparent cladding material, having a first refractive index, and wherein the first substantially transparent cladding material has embedded along its length a substantially periodic array of holes, wherein the holes are filled with a second cladding material having a second refractive index less than the first refractive index, such that radiation input to the optical fiber is transmitted along the length of the core material in a single mode of propagation. In a preferred embodiment, the core diameter may be at least 20 mu, and may be as large as 50 mu. The fiber is capable of transmitting higher power radiation than conventional fibres, whilst maintaining propagation in a single mode. The core material may be doped with a material capable of providing amplification under the action of pump radiation input to the fiber. The invention also relates to a fiber amplifier and a fiber laser comprising a doped large core photonic crystal fiber. The fiber may also be used in a system for transmitting radiation comprising a plurality of lengths of large core photonic crystal fiber, separated by large core photonic crystal fiber amplifiers, such that the power of radiation transmitted through the system is maintained above a predetermined threshold power.

A single-mode optical fiber includes a central core, an intermediate cladding, a depressed trench, and an external optical cladding. The central core has a radius r1 and a positive refractive index difference Δn1 with the optical cladding. The intermediate cladding has a radius r2 and a positive refractive index difference Δn2 with the optical cladding, wherein Δn2 is less than Δn1. The depressed trench has a radius r3 and a negative index difference Δn3 with the optical cladding. At a wavelength of 1310 nanometers, the optical fiber has a mode field diameter (MFD) between 8.6 microns and 9.5 microns and, at a wavelength of 1550 nanometers, the optical fiber has bending losses less than about 0.25×10−3 dB / turn for a radius of curvature of 15 millimeters. At a wavelength of 1260 nanometers, attenuation of the LP11 mode to 19.3 dB is achieved over less than 90 meters of fiber.

Disclosed is an optical transmission fiber having reduced bending and microbending losses that is commercially usable in FTTH or FTTC transmission systems.

A method and apparatus for obtaining three-dimensional surface measurements using phase-sensitive spectrally encoded imaging is described. Both transverse and depth information is transmitted through a single-mode optical fiber, allowing this technique to be incorporated into a miniature probe.

A single-mode optical fiber includes a central core, an intermediate cladding, a depressed trench, and an external optical cladding. The central core has a radius r1 and a positive refractive index difference Δn1 with the optical cladding. The intermediate cladding has a radius r2 and a refractive index difference Δn2 with the optical cladding, wherein Δn2 is less than the central core's refractive index difference Δn1. The depressed trench has a radius r3 and a negative index difference Δn3 with the optical cladding. The optical fiber has a nominal mode field diameter (MFD) between 8.6 microns and 9.5 microns at a wavelength of nanometers, and at a wavelength of 1550 nanometers, the optical fiber has bending losses less than 0.15 dB / turn for a radius of curvature of 5 millimeters and cable cut-off wavelengths of less than or equal to nanometers.

This invention provides a better apparatus and method for the generation of Optical Coherence Tomography (OCT) and Confocal Scanning Laser Ophthalmoscope (CSLO) images, using a dual-waveguiding module. A dual-waveguiding structure consists of a single-mode and a multi-mode waveguide each with optimum size and numerical aperture for highly efficient collection of the OCT and CSLO optical signals. Separation of the two signals is achieved by channeling most of the multi-mode guided optical power to a CSLO detector. The non-tapped single-mode guided optical wave is further sent to a pure single-mode fiber of a standard OCT system for OCT image generation. The present invention achieves highly efficient optical power usage and hence high signal to noise ratio, together with inherent pixel-to-pixel registration of the OCT and CSLO images, and a cost reduction of the OCT / CSLO combo system.

An optical fiber that is relatively insensitive to bend loss comprises a core region and a cladding region configured to support and guide the propagation of light in a fundamental transverse mode, the cladding region including (i) an outer cladding region having a refractive index less than that of the core region, (ii) an annular cladding pedestal region having a refractive index higher than that of the outer cladding region and comparable to that of the core region, and (iii) an annular cladding inner trench region disposed between the core region and the pedestal region, the inner trench region having a refractive index less than that of the outer cladding region. In one embodiment, the fiber also includes a (iv) an annular cladding outer trench region disposed between the pedestal region and the outer cladding region, the outer trench region having a refractive index less than that of the outer cladding region. In addition, to suppress HOMs the pedestal region is configured to resonantly couple at least one other transverse mode of the core region to at least one transverse mode of the pedestal region. Such fiber is advantageously used as access fiber, but may have other applications, such as sensor fiber.

A network for distributing signals to a plurality of user apparatuses having a distribution unit with a plurality of ports, and a plurality of optical-fiber cables connected to the ports and suitable to make the plurality of ports of the distribution unit communicate with the plurality of user apparatuses. At least one of the plurality of optical-fiber cables is an electrically terminated optical cable having an optical cable with a single-mode optical fiber and an opto-electronic end portion mechanically and permanently connected to an end of the optical cable, and the opto-electronic end portion has an opto-electronic conversion device having an optic port optically aligned with and mechanically connected to, an end of the single-mode optical fiber.

The present invention is a guide wire imaging device for vascular or non-vascular imaging utilizing optic acoustical methods, which device has a profile of less than 1 mm in diameter. The ultrasound imaging device of the invention comprises a single mode optical fiber with at least one Bragg grating, and a piezoelectric or piezo-ceramic jacket, which device may achieve omnidirectional (360°) imaging. The imaging guide wire of the invention can function as a guide wire for vascular interventions, can enable real time imaging during balloon inflation, and stent deployment, thus will provide clinical information that is not available when catheter-based imaging systems are used. The device of the invention may enable shortened total procedure times, including the fluoroscopy time, will also reduce radiation exposure to the patient and to the operator.

A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity. To amplify and compress optical pulses in a multi-mode (MM) optical fiber, a single-mode is launched into the MM fiber by matching the modal profile of the fundamental mode of the MM fiber with a diffraction-limited optical mode at the launch end, The fundamental mode is preserved in the MM fiber by minimizing mode-coupling by using relatively short lengths of step-index MM fibers with a few hundred modes and by minimizing fiber perturbations. Doping is confined to the center of the fiber core to preferentially amplify the fundamental mode, to reduce amplified spontaneous emission and to allow gain-guiding of the fundamental mode. Gain-guiding allows for the design of systems with length-dependent and power-dependent diameters of the fundamental mode. To allow pumping with high-power laser diodes, a double-clad amplifier structure is employed. For applications in nonlinear pulse-compression, self phase modulation and dispersion in the optical fibers can be exploited. High-power optical pulses may be linearly compressed using bulk optics dispersive delay lines or by chirped fiber Bragg gratings written directly into the SM or MM optical fiber. High-power cw lasers operating in a single near-diffraction-limited mode may be constructed from MM fibers by incorporating effective mode-filters into the laser cavity. Regenerative fiber amplifiers may be constructed from MM fibers by careful control of the recirculating mode. Higher-power Q-switched fiber lasers may be constructed by exploiting the large energy stored in MM fiber amplifiers.

The invention provides a monomode optical fiber having, at a wavelength of 1550 nm: an effective section area greater than or equal to 60 mum2; chromatic dispersion close to 8 ps / (nm.km); a chromatic dispersion slope of absolute value less than 0.07 ps / (nm2.km). In the range of wavelengths used in a WDM transmission system, typically 1530 nm to 1620 nm, the fiber has chromatic dispersions greater than 7 ps / (nm.km), thereby making it possible to limit non-linear effects. The invention also provides a WDM optical fiber transmission system using such a fiber as a line fiber. The small slope of its chromatic dispersion is an advantage in such a system.

An optical system for remotely optical communications at a high data rate between a base station and a remote station under atmospheric turbulence conditions is disclosed. The remote station includes an entirely different type of retroreflector that does not use the conventional type of retroreflection, but instead consists of two sets of lenslets coupled with single-mode fiber array, called fiber “retro”. Amplified retromodulation is achieved requiring only one single optical amplifier and one single modulator. A transmitter located at the base station sends an interrogating optical beam to the fiber “retro” which modulates the optical beam according to the input signal / data, and redirects the modulated optical beam to the base station for detection by a receiver. The present invention includes the capabilities of providing Identification of Friend-or-Foe (IFF), secure communication, and a means of achieving a wide field-of-view (FOV) with a fiber-coupled lenselet array.

An imaging guidewire that, in one embodiment, includes: (1) a hypotube forming an elongated main body having a distal end, (2) at least one multimode optical fiber integral with the hypotube and configured to carry laser light for ultrasonic excitation, (3) a single-mode optical fiber integral with the hypotube, having a reflective coating located on a distal end thereof and at the distal end of the elongated main body and configured to carry laser light for ultrasonic detection and (4) an imaging cap coupled to the elongated main body at the distal end and including a photoacoustic layer configured to receive the laser light from the at least one multimode optical fiber.

A two-channel fiber optical rotary joint has been invented in which optical signals can be transmitted simultaneously along two optical passes through a single mechanical rotational interface for both single mode fiber and multi mode fiber. The first channel of light path consists of a pair of micro-collimators, or a pair of fibers, co-axially fixed in 2 holders respectively. The light signal from one of micro-collimator, or fiber can be directly coupled into another micro-collimator, or fiber. The second channel of light path is off-axis arranged, including a pair of conventional collimators, a pair of first reflecting surfaces and a pair of second reflecting surfaces. The light signal emitted from one of the said conventional collimator will be reflected by one of the said first reflecting surface, one of the said second reflecting surface, another said second reflecting surface, and another said first reflecting surface, then coupled into another said conventional collimator. An index matching fluid is filled in the housing for lubrication and pressure compensation purposes.

The invention describes method and apparatus for a mode converter enabling an adiabatic transfer of a higher order mode into a lower order optical mode within a photonic integrated circuit exploiting integrated semiconductor ridge waveguide techniques. As disclosed by the invention, such a mode conversion is achievable by using an asymmetric coupler methodology. In an exemplary embodiment of the invention, the invention is used to provide a low insertion loss optical connection between laterally-coupled DFB laser operating in first order mode and passive waveguide operating in the zero order optical mode. The integrated arrangement fabricated by using one-step epitaxial growth allows for a launch of the laser's light into the waveguide circuitry operating in the zero order lateral mode or efficiently coupling it to single-mode fiber, an otherwise high loss interface due to the difference in laser and optical fiber modes.

A system which improves wavelength tolerance, compensates dispersion in a simple way, reduces limitation of the fiber input power is disclosed. The operation includes receiving a clock signal from a system clock source; modulating a single mode optical signal based on the clock signal and generating an optical pulse signal having two longitudinal modes, the frequency interval thereof being n×B, n being a natural number and B being a transmission speed; generating a partial response signal by converting a binary NRZ signal from a digital signal source in synchronism with the system clock source; and modulating the optical pulse signal based on the partial response signal, and outputting a binary RZ modulated signal. The binary RZ modulated signal is input into a receiver, where two partial response components in the optical spectra of the input signal are divided, and one or both of the components are received.

The invention discloses an optical fiber distributed multi-point methane real-time monitor based on the light wave modulation spectrometry and the monitoring method, a semiconductor DFB laser, an optical fiber splitter, a gas calibration pond, a laser control circuit board, a signal generative circuit board, a lock-in amplified board, a data acquisition card, a control module, a multi-channel analog signal selection switch and a driving circuit are arranged in the main case of the monitor, the main case is connected with miniature optical sensors in various underground detection optical path through dingle mode fibers. The wavelength modulation of a gas laser absorption spectrum is realized by a low frequency scanning signal and a high frequency modulation signal generated by a signal generative circuit. The laser wavelength shift is carried out adaptive adjustment by the built-in gas calibration pond so as to realize the locking of a methane absorption line. The distributed multi-point methane concentration monitoring in the underground coal mine is realized by the switching of the multi-channel analog signal selection switch.

The present invention provides an optical switch in which a switching operation is not affected even when the polarization state of a control light varies. The optical switch comprises a loop-form optical waveguide loop circuit formed from an optical nonlinear medium, control light input means of phase control means for inputting the control light into the optical waveguide loop circuit, a wavelength demultiplexing / multiplexing circuit, and a phase bias circuit. The optical waveguide loop circuit is constituted by an optical path formed from a first polarization-maintaining single-mode fiber extending from an optical demultiplexer / multiplexer to the control light input means, an optical path formed from a second polarization-maintaining single-mode fiber extending from the control light input means to the wavelength demultiplexing / multiplexing circuit, and an optical path formed from a fourth polarization-maintaining single-mode fiber extending from the wavelength demultiplexing / multiplexing circuit and returning to the optical demultiplexer / multiplexer. The wavelength demultiplexing / multiplexing circuit is formed as a loop-form optical waveguide loop circuit by a third polarization-maintaining single-mode fiber connecting a wavelength demultiplexer and a multiplexer, a fifth polarization-maintaining single-mode fiber connecting the wavelength demultiplexer and a polarization plane rotation portion, and a sixth polarization-maintaining single-mode fiber connecting the polarization plane rotation portion and the multiplexer. The phase bias circuit is inserted at a point on any one of the first through fourth polarization-maintaining single-mode fibers.

A fiber laser amplifier system including a beam splitter that splits a feedback beam into a plurality of fiber beams where a separate fiber beam is sent to a fiber amplifier for amplifying the fiber beam. A tapered fiber bundle couples all of the output ends of all of the fiber amplifiers into a combined fiber providing a combined output beam. An end cap is optically coupled to an output end of the tapered fiber bundle to expand the output beam. A beam sampler samples a portion of the output beam from the end cap and provides a sample beam. A single mode fiber receives the sample beam from the beam sampler and provides the feedback beam.

A 3D acceleration / vibration sensor for fiber grating comprises three measurement probes respectively fixedly arranged on a right plane, an upper plane and a front plane of a pedestal vertical to each other and corresponding to x, y and z axes to form a mutually vertical position relationship, wherein each measurement probe is connected with an optical splitter through a single-mode fiber at one end, and the other end of the optical splitter is respectively connected with a light source and wavelength demodulation equipment through a single-mold fiber. The measurement probe comprises a bending beam fixed on the pedestal plane, fiber gratings adhered on the surface of the bending beam along the axial direction of the bending beam and a mass block fixed on the free end of the bending beam, wherein one ends of the fiber gratings are connected with the optical splitter through a single-mold fiber. The invention adopts a fiber Bragg grating as the sensor, and adopts three fiber gratings for measuring three mutually vertical components of a spatial 3D acceleration, thus achieving measurement of the spatial 3D acceleration by vector superposition of the three components. The sensor can be used for sensing spatial 3D acceleration or vibration parameters.

The present invention directs to a method of manufacturing low water peak single mode optical fiber, which comprises performing deposition in a substrate tube using PCVD technology, whereby a deposited layer of a certain construction design is formed on the inner wall of the substrate tube, melt contracting the substrate tube into a solid core rod according to melt contraction technology, producing an optical fiber preform by combining the core rod and a jacket tube of low hydroxyl content by means of RIT technology or by depositing an outer cladding on the outer surface of the core rod using OVD technology, sending the optical fiber preform into a fiber drawing furnace to draw it into an optical fiber, wherein: in the PCVD technology, the content of impurities in a gas mixture of raw materials, which is characterized by the infrared spectrum transmissivity thereof, is required to a transmissivity of 90% or greater, the water content in O2 is 100 ppb or less, the water content in C2F6 is 1000 ppb or less, the hydroxyl content of the substrate tube is 1000 ppb or less, the dynamic leak rate of a deposition machine is 1.0×10−5 mbar·l / s or less; during melt contraction of the substrate tube, the dynamic leak rate of a melt contraction machine is 1.0×10−5 mbar·l / s or less; the hydroxyl content of the jacket tube of low hydroxyl content is required to be 10 ppm or less; the relative humidity of environment during the process of manufacture is 25% or less; the ratio of the cladding diameter to the core layer diameter (b / a value) in the waveguide structure of the optical fiber is from 2.0 to 7.0.

The present invention discloses a network architecture for upgrading a legacy time division multiplexing-passive optical network (TDM-PON) to a wavelength division multiplexing-passive optical network (WDM-PON) based next-generation passive optical network (next-generation PON), wherein the legacy TDM-PON comprises: a central office (CO) having a first optical line termination (OLT); a remote node (RN) having a splitter; a single mode fiber (SMF) connecting the first OLT and the splitter; and a first group of one or more optical network terminations (ONTs) being connected to the splitter by a first group of one or more distribution fibers, and wherein the network architecture further comprises: in case that the next-generation PON is a WDM-PON, a first apparatus for combining and splitting wavelength bands being positioned between the SMF and the first OLT, in order to add a second OLT to be used for the WDM-PON within the CO or within another CO which is located in a position different from the CO, while sharing the SMF; a second apparatus for combining and splitting wavelength bands being positioned at a front terminal of the splitter; and an arrayed waveguide grating (AWG) being connected to the second apparatus for combining and splitting wavelength bands within the RN, and being connected to a second group of one or more ONTs by a second group of one or more distribution fibers within the RN or within another RN which is located in a position different from the RN.

A microstructured optical fiber having a specially designed cladding to provide single mode waveguidance and low sensitivity to bending losses. In one aspect the optical fiber has an inner and an outer cladding each comprising elongated features. The inner cladding features have normalized dimensions in the range from 0.35 to 0.50 and the outer cladding features have normalized dimensions in the range from 0.5 to 0.9, where the normalization factor is a typical feature spacing. The fiber is further characterized by a feature spacing of the inner cladding larger than 2.0 micron. In a second aspect, the fiber has a special non-circular and non-equilateral-polygonial outer cross-sectional shape to mechanically ensure bending in predetermined directions that are favourable with respect to low bending losses. The present invention provides fibers, which are less sensitive to macro-bending losses than presently known single-mode fibers with similar sized mode areas, and provides robust, single-mode, large-mode area fibers for long-distance optical transmission and fibers with special dispersion properties.