Abstract: A single transverse mode semiconductor laser diode source is designed for employment in an optical transmission link comprising a transmitter module and a receiver module operable under uncooled conditions, i.e., without the need of costly cooling equipment, such as thermoelectric coolers. The optical transmission system includes both the semiconductor laser diode source and the optical receiver module that are both designed to operate uncooled under high frequencies (e.g., GHz range) over a wide temperature range without significant changes in signal bandwidth and at temperatures in excess of 125.degree. C.

Abstract: An optical fiber used as the active amplifying medium in a fiber laser is arranged to have a high insertion loss at an undesired frequency, while retaining a low insertion loss at a desired lasing frequency. In one embodiment, loss at a Raman-shifted frequency is introduced by using an optical fiber which has multiple claddings with an index profile that includes an elevated index region located away from the core, but within the evanescent coupling region of the core. A distributed loss, which can be enhanced by bending, is produced at the Raman frequency which effectively raises the threshold at which Raman scattering occurs in the fiber and therefore results in a frequency-selective fiber. In another embodiment, an absorbing layer is placed around the core region. The absorbing layer is chosen to have a sharp absorption edge so that it absorbs highly at the Raman-shifted wavelength, but minimally at the desired lasing wavelength.

Abstract: A semiconductor gain element has an active waveguide incident at an angle greater than normal incidence on an end facet. The waveguide may be a single stripe or may be a stripe coupled to a flared region. The waveguide may include a curved portion to produce the non-normal incidence on the end facet. The gain element may be used as the gain element within a tunable, external cavity laser, or may also be used as an amplifier to amplify an external signal. The waveguide may be formed from a central portion surrounded laterally by cladding regions. Further, absorbing regions may be positioned outside the cladding regions to absorb light that does not propagate within the waveguide.

Abstract: A semiconductor gain element has an active waveguide incident at an angle greater than normal incidence on an end facet. The waveguide may be a single stripe or may be a stripe coupled to a flared region. The waveguide may include a curved portion to produce the non-normal incidence on the end facet. The gain element may be used as the gain element within a tunable, external cavity laser, or may also be used as an amplifier to amplify an external signal. The waveguide may be formed from a central portion surrounded laterally by cladding regions. Further, absorbing regions may be positioned outside the cladding regions to absorb light that does not propagate within the waveguide.

Abstract: III-V arsenide-nitride semiconductor are disclosed. Group III elements are combined with group V elements, including at least nitrogen and arsenic, in concentrations chosen to lattice match commercially available crystalline substrates. Epitaxial growth of these III-V crystals results in direct bandgap materials, which can be used in applications such as light emitting diodes and lasers. Varying the concentrations of the elements in the III-V materials varies the bandgaps, such that materials emitting light spanning the visible spectra, as well as mid-IR and near-UV emitters, can be created. Conversely, such material can be used to create devices that acquire light and convert the light to electricity, for applications such as full color photodetectors and solar energy collectors. The growth of the III-V material can be accomplished by growing thin layers of elements or compounds in sequences that result in the overall lattice match and bandgap desired.

Abstract: A semiconductor gain element has an active waveguide incident at an angle greater than normal incidence on an end facet. The waveguide may be a single stripe or may be a stripe coupled to a flared region. The waveguide may include a curved portion to produce the non-normal incidence on the end facet. The gain element may be used as the gain element within a tunable, external cavity laser, or may also be used as an amplifier to amplify an external signal. The waveguide may be formed from a central portion surrounded laterally by cladding regions. Further, absorbing regions may be positioned outside the cladding regions to absorb light that does not propagate within the waveguide.

Abstract: An optical amplifier system includes a fiber amplifier doped with rare earth dopant provided in its fiber core. A plurality of fiber lasers have their light outputs optically coupled together for launching into the fiber amplifier for optically pumping the amplifier. Each of the fiber lasers have a rare earth dopant provided in its fiber core for stimulated lasing emission with the rare earth dopant of the fiber amplifier being different from the rear earth dopant of the fiber lasers. A reflector may be provided in each of the coupling fibers for reflecting a portion of the respective light outputs back into the fiber lasers to control their wavelength of operation, the wavelength of operation of the reflectors chosen to be within a high absorption region of the absorption band of the fiber amplifier. Where the pump source is a semiconductor laser source, the source may include a flared gain section to increase the output intensity of the light output of the source.

Abstract: Methods for aligning an optical fiber with an optical device mounted on a base include: establishing a first position of support near the optical component so as to achieve a substantially optimum alignment, then establishing a second position of support farther way from the optical component so as to refine the alignment; passing the optical fiber through an opening of a support member mounted on the base, moving the optical fiber within the extend of the opening to achieve a substantially optimum alignment, and then fixing the optical fiber to the support; and moving the optical fiber to achieve a substantially optimum alignment with the optical component, then fixing the optical fiber to a support in such a manner that any shift in position that occurs during the fixing is substantially along the optical axis of the optical fiber.

Abstract: A method of making a fiber having a single mode absorptive core whose position relative to the cross sectional plane of the inner multimode cladding varies along the length of the fiber. A groove or grooves are made in the outer cladding of the preform. When fiber is drawn from the grooved preform, the position of the core does not follow the centerline of the fiber; the position within the fiber varies in accordance with the grooves.

Abstract: Apparatus is provided for an improved stabilized laser source comprising a laser source having a light beam output and an electrical input. An optical waveguide, such as an optical fiber, having an input end is optically coupled to the laser source to receive the light beam. A reflector in the optical fiber, such as fiber grating, reflects a portion of the light beam output back into the laser source. The reflector is provided at a distance from the laser source permitting the laser source to switch between states of coherence and coherence collapse of operation. The electrical input of a drive signal for the laser source includes a modulated signal with variations in amplitude to the electrical input to control the variation in switching between the states of coherence and coherence collapse of the laser source so that continuous laser operation remains kink-free.

Abstract: A device and method for fabricating a high power laser diode device with an output emission with a nearly circular mode profile for efficient coupling into an optical fiber. A vertical taper waveguide and a window tolerance region are formed in a base structure of the device employing successive etching steps. Further regowth completes the device structure. The resultant laser device has a vertical and lateral tapered waveguide that adiabatically transforms the highly elliptical mode profile in an active gain section of the device into a substantially circular mode profile in a passive waveguide section of the device.

Abstract: An external cavity, continuously tunable wavelength source comprising a coherent light source having an external cavity including a reflector, such as a mirror or right-angle prism, for reflecting a selected wavelength from a diffraction grating back into the coherent light source. The wavelength is selected by simultaneous rotation and linear translation of the reflector about a pivot point such that the optical path length of the external cavity is substantially identical to a numerical integer of half wavelengths at a plurality of tunable wavelengths about a central wavelength of a tunable bandwidth for the source such that cavity phase error is zero at the central wavelength and is maximally flat on either side of the center wavelength within the tunable bandwidth. The location of said pivot axis is chosen to set the cavity phase error equal to zero and its first and second derivatives substantially equal to zero at exactly one wavelength.

Abstract: A number of variations are provided of a device that provides an amplified single polarization optical signal. Each of these relies on the use of a non-polarization maintaining gain medium through which the signal is directed, and a polarization shifter and reflector that direct the signal back through the same gain medium with a shifted polarization state. An input polarization beamsplitter directs the returning optical signal away to an output, based on its shifted polarization state. The embodiments of the invention include the use of double-clad fiber. Multiple stages may be used to provide specific amplification parameters. In one embodiment, both amplification stages reside in the same polarization shifting optical path. A polarization maintaining amplifier of this type may be used as part of a master oscillator-power amplifier, in which polarization maintaining fiber is used as part of the source laser.

Abstract: A fiber Bragg grating is used to stabilize the intensity and frequency fluctuations of a diode laser. The diode laser is connected with an opto-mechanical apparatus to the fiber which contains the grating. The grating is formed in the guided-mode region of the optical fiber. The wavelength of maximum grating reflectivity is selected to lie near the maximum of the diode laser gain bandwidth. The magnitude and bandwidth of the grating reflectivity stabilizes the diode laser output without appreciably reducing the optical output power from the end of the fiber. The bandwidth of the optical spectrum of the diode laser is selected depending on the distance of the grating from the diode laser.

Abstract: A system and method for operating a high power laser diode device with high efficiency coupling of a laser diode bar. The laser diode bar and a micro-cylinder lens are vertically oriented in a device package, such that the array axis of the laser bar and the longitudinal axis of the micro-cylinder lens are aligned substantially parallel to a gravity vector. In the two different embodiments disclosed, either initial collimation of the fast-axis divergence or, alternatively, initial collimation of both the fast-axis and slow-axis divergences take place before beam reformatting via a beam array turning mirror. Additionally, the vertical orientation of these components is combined with methods of compensating for the bending or "smile" of the laser diode bar to provide for optimal output beam coupling, resulting in a uniform far field intensity distribution.

Abstract: A fiber laser or fiber amplifier uses resonant pumping of the gain medium by providing a pump resonator that establishes a resonator cavity at the pump wavelength which includes the pumped gain medium. The pump resonator may be of a distributed feedback (DFB) or a distributed Bragg reflector (DBR) type construction, and may be combined with signal reflection apparatus of either DFB or DBR type construction that provides oscillation of the desired laser output wavelength. If used without a signal reflection apparatus, the invention may be operated as a resonant pumped fiber amplifier. Resonant pumped lasers may be arranged in series to provide a laser apparatus with a selectable output wavelength. The different laser stages each provide resonance for a different pump wavelength, and each provide resonance for a different signal wavelength.

Abstract: Apparatus for stabilizing multiple laser sources having distinguishable optical characteristics, e.g., in polarization field or operational wavelength, comprises a plurality of semiconductor laser sources having respective lasing cavities capable of lasing within a narrow bandwidth of wavelengths and providing spectral outputs at their respective laser exit facets having different optical characteristics from one another. The spectral output beams of the sources may be coupled to respective optical fibers and the beams combined via a beam combiner, e.g., a polarizing beam combiner or a WDM combiner. The beam combiner combines the beam outputs forming a single beam which is launched into an output optical fiber. At least one feedback fiber grating is provided in at least one of the optical fibers with the number thereof depending upon distinguishable optical characteristics of the multiple laser sources.

Abstract: A beam reconfiguring device comprises a single prism element that reconfigures a beam input, such as from a semiconductor laser or bar array, having aperture images with major axis aligned abreast along a single axis, into an output comprising multiple segments of the input image with a major axis of each segment aligned perpendicular along the same single axis. The etendue, the aperture-times-divergence product of a beam, in orthogonal directions of the output beam will be more nearly equal than the etendue in orthogonal directions of the input beam. The input beams and reconfigured beams are provided as adjacent inputs to a hypotenuse front edge surface of the prism element. The reconfigured beams are more conducive for converging into a single substantially symmetrical spot for input to an optical handling device or medium such as an optical fiber. An optical handling system is disclosed for achieving straight in-line, beam input/output that is more adaptable for optically aligned delivery applications.

Abstract: An infrared laser diode wireless local area network for communication between spatially dispersed terminals such as computers which may be located in a single room or in adjacent rooms. The lasers may be tuned to emit at varying frequencies for wavelength multiplexing, or a plurality of lasers each having a different output frequency can be connected with each terminal. A receiver connected to each terminal may similarly detect only a single narrow waveband or may detect a plurality of such wavebands. A transceiver may be employed for signal transmission between separate rooms. High speed data modulation of the carrier waves is provided with MOPA or similar lasers, and broad angular dispersion of the output is achieved by such lasers along with dispersive lenses.

Abstract: An AlGaInP/GaAs laser diode is disclosed in which the active region is made up of quantum wells that are sufficiently thin (less than 5 nm thick) that the transition energy increase due to quantum confinement of the carriers becomes significant. This allows the quantum well material composition to be selected for compressive strain so that the laser operates in the TE polarization mode, while still obtaining a transition energy of from 1.9-2.0 eV for 620-650 nm laser emission. Quantum barriers have sufficient thickness to confine carriers to the quantum wells. Self-pulsation may be obtained in a heterostructure that also includes a saturable absorption layer proximate to the active region and a ridge structure transversely confining absorption produced carriers in the central section of the absorber layer, while allowing lateral carrier diffusion to side regions where carriers are allowed to leave the absorber layer.