Abstract: A semiconductor laser source having a laser diode and a fiber Bragg grating is described. The laser diode has first and second facets from which output light is emitted. A first end of the fiber Bragg grating is located near the second facet to receive output light from the laser diode. The fiber Bragg grating has a very narrow linewidth about a selected wavelength and reflects output light in the selected narrow linewidth back into the laser diode through its second facet. The output light emitted from the first facet has a very narrow linewidth about the selected linewidth.

Abstract: A fiberoptic coupler capable of many functions is presented. The basic fiberoptic coupler has a first sleeve, a second sleeve, a first collimating GRIN or conventional lens, and a second collimating GRIN or conventional lens. The first sleeve holds end sections of two or more input optical fibers along the longitudinal axis of the sleeve. The second sleeve holds an end section of at least one output optical fiber. The end face of the second sleeve faces the first sleeve end face. The first collimating GRIN or conventional lens in front of the first sleeve end face collimates light signals from the input optical fibers and the second collimating GRIN or conventional lens in front of the second sleeve end face focusses light signals from at least one of the input optical fibers into the single output fiber, or at least one of the output optical fibers. With only one output fiber the coupler operates as a combiner.

Abstract: A fiberoptic coupler capable of many functions is presented. The basic fiberoptic coupler has a first sleeve, a second sleeve, a first collimating GRIN or conventional lens, and a second collimating GRIN or conventional lens. The first sleeve holds end sections of two or more input optical fibers along the longitudinal axis of the sleeve. The second sleeve holds an end section of at least one output optical fiber. The end face of the second sleeve faces the first sleeve end face. The first collimating GRIN or conventional lens in front of the first sleeve end face collimates light signals from the input optical fibers and the second collimating GRIN or conventional lens in front of the second sleeve end face focusses light signals from at least one of the input optical fibers into the single output fiber, or at least one of the output optical fibers. With only one output fiber the coupler operates as a combiner.

Abstract: A fiberoptic network transmission system combines the output signals of several laser sources into a single optical fiber. The transmission system has integrated optical isolator couplers which each have at least two input optical fibers and an output optical fiber. Each input optical fiber is connected to a laser source and the output optical fiber is connected to an input terminal of a combiner which has its output terminal connected to the single optical fiber. The integrated optical isolator couplers block light from the single optical fiber from reaching any of the laser sources.

Abstract: A fiberoptic amplifier system having an optical amplifier, which receives an input signal and generates an amplified signal and amplified spontaneous emission noise, and a variable polarization beam splitter, which receives the amplified signal and amplified spontaneous emission noise from the optical amplifier. The amplified spontaneous emission (ASE) noise is a broadband optical noise with a random polarization state in a rare earth-doped fiber optical amplifier. In a semiconductor laser diode optical amplifier, the ASE noise is partially polarized depending upon the waveguide structure of the laser diode.

Abstract: The present invention provides an improved clip for supporting an end of an optical fiber relative to a mount surface. Typically, a sleeve is disposed over the optical fiber adjacent to its end. The clip comprises a clip body having upper and lower surfaces with a flange disposed adjacent to the lower surface. The flange is affixable to the mount surface, and walls extend from the upper surface of the body to define a channel at which the clip is affixable about the sleeve. Advantageously, when the sleeve is affixed within the channel, the body rigidly couples the sleeve to the flange, thereby avoiding misalignment between the optical fiber and any optical device which is on or supported by the mount surface.

Abstract: An improved optical switch having a first optical fiber and a plurality of N optical fibers. The first optical fiber forms an optical path with any one of the N optical fibers by an alignment of a longitudinal axis of an end of the first optical fiber with a longitudinal axis of an end of the one of N optical fibers. A switch in optical path is performed by a relative movement of the first optical fiber with respect to the N optical fibers for a realignment of the longitudinal axis of the end of the first optical fiber with a longitudinal axis of an end of another one of the N optical fibers.

Abstract: A low-cost, high performance 1.times.N fiber optic coupler where N>16 is presented. The coupler has a GRIN lens having an first optic fiber aligned with the optical axis of the lens at one end of the lens. The first optic fiber ends in a microlens. At the other end of the GRIN lens a bundle of tapered second optic fibers is centered on the optical axis of the lens.

Abstract: The present invention provides for a two-stage optical isolator with reduced polarization mode dispersion. Each stage has two birefringent polarizers separated by a Faraday rotator. The polarizers in each stage are oriented with respect to each other to operate conventionally as an optical isolator for light in a backward direction. However, the polarizers in each stage are oriented with respect to the polarizers in the other stage so that a polarization mode along one direction, say, the ordinary direction, of light in the first stage travelling toward the second stage is aligned along the opposite, extraordinary, direction in the second stage and vice versa. In this manner the component of any polarization travels the same optical distance through the optical isolator to substantially reduce polarization mode dispersion.

Abstract: The present invention provides for a two-stage optical isolator with reduced polarization mode dispersion. Each stage has two birefringent polarizers separated by a Faraday rotator. The polarizers in each stage are oriented with respect to each other to operate conventionally as an optical isolator for light in a backward direction. However, the polarizers in each stage are oriented with respect to the polarizers in the other stage so that a polarization mode along one direction, say, the ordinary direction, of light in the first stage travelling toward the second stage is aligned along the opposite, extraordinary, direction in the second stage and vice versa. In this manner the component of any polarization travels the same optical distance through the optical isolator to substantially reduce polarization mode dispersion.

Abstract: A low-cost, high performance 1.times.N fiber optic coupler where N>16 is presented. The coupler has a GRIN lens having an first optic fiber aligned with the optical axis of the lens at one end of the lens. The first optic fiber ends in a microlens. At the other end of the GRIN lens a bundle of tapered second optic fibers is centered on the optical axis of the lens.

Abstract: The present invention provides for a compensating element in the form of a birefringent plate in an optical isolator which uses a first GRIN lens to collimate the light signal from an input optical fiber, a first birefringent polarizer wedge, an optical Faraday rotator, a second birefringent polarizer wedge, and a second GRIN lens to recollimate the light signal to an output optical fiber. Polarization mode dispersion through said optical isolator is substantially reduced by arranging the fast optical axis of the plate to be perpendicular to the fast optical axis of the polarizer on the same side of the Faraday rotator as the plate and selecting the thickness of the plate in a predetermined manner. The present invention also allows for minimization of "walk-off", which also contributes to some polarization mode dispersion through the isolator.

Abstract: Wavelength division multiplexed couplers are provided with the ends of input and output optical fibers arranged with respect to GRIN lens so that light from one input fiber is directed toward one output fiber with little crosstalk. An integrated wavelength division multiplexed coupler and isolator device useful for connecting fiberoptic amplifiers to pump lasers is also provided with one version of the WDM coupler. The integrated WDM coupler and isolator device has a tap coupler component created by a planar grating which deflects a small portion of the light through the device toward a photodetector circuit for monitoring purposes. The integrated device also may be combined with a laser diode subassembly can be combined to eliminate a pump laser connection for the fiberoptic amplifier.

Abstract: A low-cost, high performance 1.times.N fiber optic coupler where N>16 is presented. The coupler has a GRIN lens having an first optic fiber aligned with the optical axis of the lens at one end of the lens. The first optic fiber ends in a microlens. At the other end of the GRIN lens a bundle of tapered second optic fibers is centered on the optical axis of the lens. The microlens is formed by fusing two fibers together, stretching the fused region, jerking the fibers apart and then heating a fiber end to form the lens.

Abstract: An optical fiber having an improved input fiber end for an optical isolator. The end of the fiber has a flat end surface substantially perpendicular to the longitudinal axis of the fiber. An optical barrier layer, formed by a layer of chromium and a layer of gold, covers the end surface of the fiber with an aperture exposing the core and covering the cladding of the fiber. Light transmission into the end is substantially reduced to increase the reflection loss of the optical isolator.

Abstract: An improved optical switch having a first optical fiber and a plurality of N optical fibers. The first optical fiber forms an optical path with any one of the N optical fibers by an alignment of a longitudinal axis of an end of the first optical fiber with a longitudinal axis of an end of the one of N optical fibers. A switch in optical path is performed by a relative movement of the first optical fiber with respect to the N optical fibers for a realignment of the longitudinal axis of the end of the first optical fiber with a longitudinal axis of an end of another one of the N optical fibers.

Abstract: A semiconductor laser diode is optically coupled to an electro-optic phase modulator and an electrical control signal is applied to the phase modulator to modify its optical gain or loss and its real refractive index, to in turn alter the optical length of the modulator and shift its resonant wavelengths. The result is to tune the laser diode. A facet of the laser diode is anti-reflection coated to minimize interface loss between the laser diode and the phase modulator.

Abstract: A torch specifically adapted for the manufacture of optical fiber couplers is provided. The torch has a rod and nozzle of, preferably machinable, ceramic. The rod has an inlet for connection to a gas supply source, an outlet, and a gas channel connecting the inlet to the outlet. The nozzle has an inlet for receiving gas from the rod outlet, and an enlarged outlet connected to the nozzle inlet for discharging gas for ignition. The shapes and dimensions of the parts of the torch can be modified for the specific manufacturing requirements for an optical fiber coupler. During the manufacture of optical fiber couplers, the torch can be maintained in an ignited state so that the fusing of optical fibers can be performed uniformly and reliably.

Abstract: The present invention provides for a workstation for automatically manufacturing a coupler between at least two optical fibers. The workstation has a control unit for directing operations of said workstation and an operations unit for performing the manufacturing steps for the coupler. The operations unit has a pair of clamps for holding the optical fibers for the formation of a coupling region between the clamps, a torch for heating a predetermined length of the fibers between the clamps to fuse the fibers, motor assemblies responsive to the control unit for driving the clamps, a source laser block for generating an input signal into the optical fibers, and a laser measurement block which measures the signal from laser source block to determine characteristics of the coupling region between the optical fibers.

Abstract: An improved optical isolator of the type having an input optical fiber, a first GRIN lens, a first polarizer, a optical rotator, a second polarizer, a second GRIN lens and an output optical fiber. Lithium niobate birefringent crystals are used for lowered costs and high performance. Improvements also include polishing the end of the input optical fiber at a slant and covering the end with a window coated with antireflection material. The surface of the GRIN lens facing the end of the input optical fiber is slant-polished reciprocally and spaced apart with gap which avoids Fabry-Perot interference.