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 translational movement 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: An erbium/ytterbium fiber amplifier amplifying an optical signal at approximately 1550 nm is pumped by an optical signal at approximately 1060 nm generated by a grating-stabilized ytterbium fiber laser. The fiber laser energy is output along a first optical path, which is coupled to the fiber amplifier coil via a WDM coupler. An optical attenuator is located in the optical path between the fiber laser and the fiber amplifier coil, and attenuates optical energy in the wavelength range of 1090 nm, to prevent optical coupling in that range between the fiber laser and the fiber amplifier from destabilizing the fiber laser. In one embodiment, the optical attenuator is a narrowband WDM coupler which couples wavelengths in the selected range out of the optical path. In another embodiment, the optical attenuator is a long-period optical fiber Bragg grating which attenuates the selected wavelengths.

Abstract: An optical transmission link has both 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 a semiconductor laser diode source and an 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. Compensation is provided to reduce the effect of photodiode noise and amplifier noise. In addition, temperature compensation can be provided that provides for overall reduction in receiver noise across the bandwidth of the receiver module through maintenance of a temperature environment optimizing receiver performance.

Abstract: An optical amplifier pumping system with built-in redundant reliability for lightwave communication system provides plural levels of redundancy. A first level of redundancy deals with redundancy in the form of plural primary laser diode sources in the lightwave communication system. A second level of redundancy deals with redundancy of multiple single mode laser emitters on the same chip or bar sufficiently segmented so as not to interfere with operation of or cause failure to adjacent or neighboring emitters on the same chip or bar. A third level of deals with redundancy of a plurality of fiber pump sources for pumping a plurality of serially connected injection signal fiber amplifiers.

Abstract: An optical device for modulating or interacting with radiation guided and propagating along an optical longitudinal axis of an optical waveguide, such as, an optical fiber, has a different directional geometry compared to conventionally comparable devices such as, for example, plasmon or planar surface modulators for optical fibers. The geometry includes a nonlinear, electro-optic medium formed between two spatially disposed electrodes. The medium/electrode sandwich is aligned along the waveguide longitudinal propagating axis and extends in a radial direction from the optical waveguide core with the inner end of the medium in spatial proximity to the waveguide core for evanescent coupling with the radiation field propagating in the waveguide.

Abstract: An optical amplification system directs a diffraction-limited signal beam through a series of approximately 90.degree. crossings with a number of non-diffraction-limited pump beams in a photorefractive medium. All of the beams are s-polarized, resulting in an energy transfer from the pumps to the signal beam while leaving the signal beam diffraction-limited. The photorefractive medium is preferably a series of BaTiO.sub.3 :Rh crystals that receive the pump and signal beams through orthogonal faces, with their C-axes at approximately 45.degree. to both beams. A binary tree optical distribution network is used to minimize waveguide splits in forming a large number of pump beams.

Abstract: A travelling-wave semiconductor laser amplifier having suppressed self-oscillation is provided. When incorporated into a master oscillator power amplifier device, such a device has improved light output versus amplifier current characteristics. Also provided is a method for suppressing self-oscillation in travelling-wave semiconductor laser amplifier structures for improving the characteristics of the device into which the amplifier is incorporated.

Abstract: A fibre 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 fibre which contains the grating. The grating is formed in the guided-mode region of the optical fibre. 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 fibre. 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 vehicle lighting system using individually addressable laser diodes or laser arrays coupled to a fiber optic waveguide. A plurality of laser light sources are grouped together and conveniently located on the vehicle. Each laser light source is individually addressable and produces a beam that is coupled to a fiber optic waveguide. The waveguide distally transmits the beam to various optical loads on the vehicle. Alternatively, each fiber optic waveguide may be coupled to receive a beam from more than one laser light source. This allows switching to an operational light source should one fail. In this manner, the operational life of the system is increased.

Abstract: Apparatus for generating laser light having a wavelength in the range of about 1012 to 1022 nm comprising a double clad optical fiber having a core doped with triply ionised ytterbium ions, a source of laser light emitting at a wavelength of about 800 to 1070 nm and coupled to launch the fight into the fiber, and fiber Bragg gratings written into the core region of the optical fiber so as to provide optical discrimination of the emission centered in the range of about 1012 to 1022 nm.

Abstract: A semiconductor laser having a light amplifying diode heterostructure body having a single spatial mode aperture region or waveguide and a flared or tapered gain region having a narrow input end and wider output end provided in a resonant cavity, a portion of which cavity may be external of the body. The flared gain region has a narrow aperture end and a wide output end with narrow aperture end optically coupled to a single mode waveguide. A saturable aborbing region is formed as part of the single mode waveguide region and not between it and the flared gain section, and is reverse biased to provide for mode locked operation. The flared gain region and waveguide may be differentially pumped or modulated with current provided by separate contacts, and the flared gain region may be divided into one or more flared gain sections which may be differentially or separately pumped.

Abstract: An optical coupling system for improving the coupling efficiency of an elliptical light beam into optical fiber comprises a cylindrical concave microlens on the end facet of the optical fiber in conjunction with a pair of bulk optic asphere lenses. A method of producing a cylindrical concave microlens according to the invention consists of translating a fine wire across the end facet of an optical fiber so as to create a cylindrical grove.

Abstract: A wavelength tunable, semiconductor laser includes a gain region, e.g., a flared amplifier region, that permits light propagation with a diverging phase front along at least a portion of the gain region. Optical feedback defines a resonant laser cavity that has a first reflector at a first end of the cavity a second reflector at a second end of the cavity for reflecting at least a portion of the light back propagating in the cavity back into the cavity. Wavelength tuned selection, such as through orientation of a grating reflector or via a prism, is provided in the resonant laser cavity for producing a relatively lower optical loss in the cavity to a selected wavelength or a band of wavelengths of the light propagating within the cavity relative to other nonselected wavelengths such that stable laser oscillation is established at the selected wavelength or band of wavelengths.

Abstract: III-V arsenide-nitride semiconductor crystals, methods for producing such crystals and devices employing such crystals. 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 crystals 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.

Abstract: An upconversion fiber laser uses a pump source which may be another fiber laser, such as a high power, diode-laser-pumped, fiber laser. The upconversion fiber laser includes an optical fiber whose core region is doped with an active lasing ionic species capable when optically pumped of undergoing upconversion excitation, such as certain rare earth ionic species, and which is embedded in a cladding of the optical fiber. Use of a fiber pump laser can improve coupling of pump light into the optical fiber, thereby achieving higher pump intensities in the core region and improved upconversion efficiency. The upconversion fiber laser's resonant laser cavity is defined by feedback means which can include at least one reflective grating formed in the optical fiber, as well as a reflective end face of the optical fiber.

Abstract: A fibre 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 fibre which contains the grating. A polarization maintaining fibre is used. The grating is formed in the guided-mode region of the optical fibre using photorefractive techniques. 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 is sufficient to stabilize the diode laser output without appreciably reducing the optical output power from the end of the fibre. The bandwidth of the optical spectrum of the diode laser is increased or decreased relative to the solitary diode laser operating characteristics depending on the distance of the grating from the diode laser.

Abstract: In an optical transmission medium, such as a fiber amplifier, two optically distinguishable signals with complementary modulation are both inputted into the amplifying medium for encoding information, particularly a serial stream of digital data, or alternatively, redundant encoding of pulses. The gain profile in the medium is preferably maintained approximately constant at all times, so that whichever amplified signal is used as the primary information carrier, its output intensity will be substantially stable from pulse to pulse, independent of recent pulse history. The two complementary signals may have different orthogonal linear polarizations or wavelengths with the same stimulated emission cross-section, so that the population inversion profile stays constant, whichever signal happens to be on at a given moment.

Abstract: A semiconductor light amplifying medium has reduced self-focusing and optical filamentation for providing higher power coherent outputs in broad-area laser and amplifier devices. In one embodiment, a longitudinally inhomogeneous active region has alternating segments of first gain portions and second compensating portions. The compensating portions have a negative self-focusing parameter [.differential.n/.differential.P] and may be light absorbing (negative gain) regions with negative antiguiding factor .alpha. or light amplifying (positive gain) regions with positive antiguiding factor .alpha.. The .alpha.-parameter is defined as the ratio of refractive index change per change in gain, as a function of carrier density. In a second embodiment, the medium may have longitudinally varying peak filament period so that filaments beginning to form in one portion of the active region are subsequently dispersed in a succeeding portion, slowing filament growth.

Abstract: A wavelength-stabilized, semiconductor laser having a light amplifying diode heterostructure with a flared gain region in an external resonant cavity. The flared gain region has a narrow aperture end which may be coupled to a single mode waveguide and a wide output end. A light emitting surface of the heterostructure proximate to the Wide end of the flared gain region is partially reflective and combines with an external reflector to form a resonant cavity that is effectively unstable. The intracavity light-emitting surface proximate to the narrow aperture end is antireflection coated. The external reflector may be a planar mirror or a grating reflector. A lens or an optical fiber may couple the aperture end of the flared gain region to the external reflector. Frequency-selective feedback is provided by orienting the grating reflector or providing a prism in the cavity in front of the external planar mirror. Other filtering elements may also be placed in the external cavity.

Abstract: A harmonic generator laser system which features a distributed Bragg reflector (DBR) or distributed feedback (DFB) tunable diode laser coupled to a quasi-phasematched (QPM) waveguide of optically nonlinear material. Tuning of the DBR laser may be achieved either thermally or via current injection, or both, halving the wavelength of a red laser into the visible blue spectral band. Thermal tuning may provide a coarse tuning adjustment, while injected current may provide fine tuning accessible to a user. Separately or in combination with current tuning, a modulation signal may be applied to the DBR laser for achieving an intensity modulated or a pulsed output. In another embodiment, modulation may be achieved by frequency modulation of the laser. A very compact tunable blue laser is formed. In yet another embodiment a double clad fiber amplifier is disposed between the tunable laser and the waveguide.