Abstract: Optical semiconductor devices with integrated diffraction gratings with higher quality are realized through the use of Al-free grating layers. AlGaAs/GaAs regime optical semiconductor devices, such as laser diodes or optical filters, conventionally utilize an AlGaAs grating layer that has a strong affinity for oxidation. Instead of a Al-containing layer, a quantenary, InGaAsP grating layer is utilized, lattice matched to the underlying AlGaAs/GaAs structure, substantially eliminating any problem of oxide contamination. Also, an Al-free, ternary InGaP grating layer is utilized in the InGaP/InGaAsP/GaAs material regime. The quantum well active region of these devices may also be modified to extend the gain bandwidth of operation of these devices to insure continued operation over a wider temperature range with the wavelength peak of the grating in that the wavelength peak of the grating more assuredly remains within the wavelength operating range of the device.

Abstract: A method of manufacturing a p-type III-V nitride compound semiconductor utilizing vapor phase epitaxy is carried out in a MOCVD reactor by growing a III-V nitride compound semiconductor in the reactor employing a reaction gas containing a p-type impurity and then annealing in-situ the nitride compound semiconductor to bring about acceptor activation, the annealing carried out at a temperature below the growth temperature of the III-V nitride compound semiconductor during reactor cooldown. A nitrogen (N) reactant or precursor is provided in the reactor during the annealing step which can produce a reactive form of N capable of suppressing surface decomposition and does not produce atomic hydrogen. Also, acceptor activation is achieved through the employment of a cap layer comprising a n-type Group III-V nitride material, e.g., n-GaN, grown on the p-doped Group III-V nitride layer preventing the occurrence of hydrogenation of the underlying p-doped layer during cooldown.

Abstract: A high-power two-dimensional edge-emitting diode laser array comprises mounting modules, laser bars mounted on the modules, and protective caps mounted on the bars opposite the modules. The lasers are electrically connected in series through the modules and caps. The caps serve as laser bar protectors during the bar burn-in. The caps have grooves which compensate for tolerances in the thicknesses of the lasers, modules, and caps. The array is mounted on a base plate, and is in thermal communication with a heat sink. The caps and/or modules are thermal-expansion-matched to the laser bars. Eliminating the need for a wire bond plate allows shortening the modules.

Abstract: A WDM communication system utilizes a pump-mediated gain-shaped fiber amplifier having a predetermined nominal signal gain bandwidth and is pumped by a plurality of laser pump sources having different wavelength outputs with their outputs combined to provide a scaled power output of a weighted average of their wavelengths for launching into at least one end of the fiber amplifier. The weighted average of the output wavelengths of the individual sources is varied to produced a modified weighted average that broadens the predetermined nominal signal gain bandwidth. The wavelength weighted average of the combined pump sources may be modified by changing the operation of at least one of the pump laser sources, e.g., by changing the power level or the temperature level of one or more of the individual pump sources or by terminating the operation of one or of the individual pump sources.

Abstract: A thermal compensator for stabilization of the operation of a waveguide DBR laser against changes in its operational parameters due to operational temperature changes so that thermally induced longitudinal mode hopping in the laser is suppressed and, in addition, the desired operational wavelength may be stabilized.

Abstract: A semiconductor gain medium has an optical cavity comprising a multimode region permitting propagation of light with a diverging phase front and a single mode region. An optical cavity is formed by optical feedback within the medium. Preferably, the feedback comprises a combination of a cleaved facet and a grating. The gain medium may be an amplifier or, in addition to the amplifier, may include a resonator cavity, or operate as an unstable resonator.

Abstract: Laser diode pumped mid-IR wavelength systems include at least one high power, near-IR wavelength, injection and/or sources wherein one or both of such sources may be tunable providing a pump wave output beam to a quasi-phase matched (QPM) nonlinear frequency mixing (NFM) device. The NFM device may be a difference frequency mixing (DFM) device or an optical parametric oscillation (OPO) device. Wavelength tuning of at least one of the sources advantageously provides the ability for optimizing pump or injection wavelengths to match the QPM properties of the NFM device enabling a broad range of mid-IR wavelength selectivity. Also, pump powers are gain enhanced by the addition of a rare earth amplifier or oscillator, or a Raman/Brillouin amplifier or oscillator between the high power source and the NFM device. Further, polarization conversion using Raman or Brillouin wavelength shifting is provided to optimize frequency conversion efficiency in the NFM device.

Abstract: A semiconductor laser having a light amplifying diode heterostructure with a flared gain region in an narrow aperture end whoch 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: An optical system for coupling an output beam in an alignment direction from a semiconductor device output beam from a semiconductor device through a lens arrangement to focus the beam onto a center point of an input end surface of an optical transmission medium. The optical system includes a steering lens positioned between the semiconductor device and a focusing lens with the center of the steering lens in relative axial alignment with the output beam and may be laterally translated in a direction transverse to the axial direction of said beam for initially aligning the focused point of said beam in close proximity to said center point.

Abstract: A hermetically sealed package for an optoelectronic device such as a diode laser comprises a side wall welded to a thermally conductive heat sink mount, and a lid welded to the side wall. Testing and alignment of the device are performed before the attachment of the side wall to the mount. Feedthroughs for optical fibers and electrical connections run through the side wall. The feedthrough seals are established within projections extending away from the side wall, to protect the seals from melting during welding steps. A high-resistivity piece is present at the interface between the side walls and the base, to provide heating localized to the interface, and thereby reduce the heating of the laser during welding. The mount is pressed into a receiving structure, which is attached to an external heat sink. The bottom surface of the mount protrudes from the receiving structure, and is in direct contact with the external heat sink.

Abstract: A waveguide DBR laser or waveguide DBR laser array may be comprised of a semiconductor gain element, or a series of semiconductor gain elements, in combination with a waveguide grating functioning as a resonant cavity end reflector for lasing operation comprising either an optical fiber having a fiber grating (fiber DBR laser) or a planar waveguide (planar waveguide DBR laser). The gain element may be comprised of a laser diode which has high efficient AR coating on its front facet so that it functions as a modulated gain element in a resonant cavity established between its rear HR facet and the grating formed in the external waveguide.

Abstract: Two approaches are provided for achieving an optical amplifier system capable of producing high peak power, high energy pulse outputs while suppressing scattering noise. The first approach relates to an optical amplifier system which has at least one laser diode pulsed or cw pumped double clad fiber amplifier utilized for receiving a high frequency modulated injected signal pulse of short duration from the laser diode, via the fiber core, for amplification by coupling pump light into the inner cladding of the fiber. The average signal power is sufficient to saturate the gain of the fiber so as to minimize significant onset and buildup of forward and backward scattering noise. The duty cycle of the injected signal source pulse is chosen to allow adequate gain recovery in the fiber amplifier between pulses.

Abstract: A semiconductor gain medium has an active gain region with a partially patterned radiation diverging region. The partially patterned radiation diverging region may be created with spatial resistive regions formed in a portion of the radiation diverging region having a narrower width than in other portions of the diverging region where the propagating radiation has a greater width. The gain region may be an amplifier or, in addition to the amplifier, may include a resonator cavity, or operate as an unstable resonator.

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.

Abstract: A mounting module (submount) for a high-power heat-dissipating element comprises a mounting plate thermal-expansion-matched to the element, a high-thermal-conductivity bulk layer having stress-relief apertures, and an auxiliary plate bonded to the bulk layer opposite the mounting plate. The element is mounted on the mounting plate, while the bulk layer is attached to the mounting plate on the side opposite the element. The apertures accommodate the expansion of the bulk layer along a major dimension of the mounting plate. The apertures run transverse to the mounting plate, so as not to impede heat flow through the mounting plate. The apertures serve either as reservoirs for excess solder during module assembly, or as conduits for cooling fluid. The bulk layer comprises either stacked sheets having aperture sections defined prior to assembly, or blocks defining the apertures at the block interfaces.

Abstract: A heatsink and an optical system are provided for use in conjunction with a dissipating semiconductor or electronic device, such as a light source, that generate a large amount of heat and is required to be cooled for optimum performance. The light source may be a laser diode or laser array or bar and is generally mounted on the heatsink with other optical components, such as collimating and focusing lenses, isolators or terminal ends of optical fibers, for coupling the output beam of the light source in aligned relation to these optical elements. Because of the higher temperature operation of such light sources, the heat generated causes thermal expansion of mechanically connected structures, such as between the heatsink for supporting the light source and its associated submount and an underlying support, usually a cooler.

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 cooler features a plurality of microchannels each of which includes a plurality of baffles disposed therein to avoid laminar flow within each microchannel through modulation which varies both the direction and velocity of fluid flowing through each microchannel. The microchannels are formed between a plurality of spaced apart thermally conductive fins, which are arranged to extend from a thermally conductive substrate adapted to be in physical contact with a region to be cooled. The fins are formed by stacking a plurality of thin sheets along a direction transverse to a longitudinal axis of the microchannels. Each sheet includes a plurality of apertures spaced apart along two transverse directions, both of which are transverse to the stacking direction. The baffles are formed from the spaces disposed between the apertures. Preferably, each sheet is formed from copper which is chemically etched to form the apertures in the sheet.

Abstract: A diode laser source including a laser diode whose emitting element array or elements or subarray is divided into a plurality of concurrently driven laser segments. Beam filling and focusing optics are disposed in front of the segments so that light from the segments in each element or subarray converges to a single overlapping spot. The optics include a beam filling lens array collimating the light from the segments and either a single focusing lens or a second lens array focusing the collimated light to corresponding spots. In the case of a element laser diode array, each multi-segment element or subarray of the array is individually addressable so as to be driven independently from the other multi-elements array elements. The segmentation of laser elements improves laser life by reducing thermal gradients and isolating any local failures to a single segment, while separately focusing of the segments of each subarray to overlapping light spots increases the tolerance of the source to local failures.

Abstract: A laser system is provided for supplying high power, stable light intensity via an aperture limited delivery system to an application requiring continuous light output intensity in spite of the laser source being subjected optical feedback noise caused by external system and delivery system perturbations that cause fluctuation in laser source power intensity. Non-stable light intensity in the output is due to environmental temperature changes, and phase and amplitude changes caused by system induced perturbations such as by movement of the aperture limited delivery system and optical artifacts of the optical elements, comprising the aperture limited delivery system, introducing noise into the feedback in the laser system changing the output intensity pattern of the delivered power beam. This can be substantially remedied by the employing a monolithic, multiple, independent single mode laser source which is substantially unaffected by this noise.