Abstract: An improved semiconductor structure is provided. The semiconductor structure comprises a first layer, the first layer having a restricted growth surface having a region with a transverse dimension D, the first layer having a first lattice constant L.sub.1 ; a first, last and at least one intermediate transition layers, the transition layers forming a transition region, the transition region disposed above the first layer, the transition region having a vertical thickness T, and where at least one of the transition layers has lattice constants between L.sub.1 and a second lattice constant L.sub.2 where the first transition layer has a lattice constant closer to the L.sub.1 than L.sub.2 and the last transition layer has a lattice constant closer to the L.sub.2 than L.sub.1 ; and a second layer disposed on the transition region, the second layer having the second lattice constant L.sub.2 ; wherein: the transition region has an average fractional change in lattice constant characterized by .kappa. where .kappa.

Abstract: A monolithically integrated vertical twin-waveguide structure reduces the sensitivity of the device performance characteristics due to the laser cavity length and variations in the layer structure. This is achieved by the introduction of an absorption or loss layer between the active and passive regions. This layer eliminates the propagation of the even mode, while having minimal effect on the odd mode. The threshold current densities and differential efficiencies of the devices are unaffected by the loss layer. A coupling efficiency of 45% from the laser to the external passive waveguide is obtained.

Abstract: An optical recording/reproducing apparatus has a laser diode and a semiconductor integrated circuit device for driving the laser diode. The semiconductor integrated circuit device has a driver circuit for producing a drive current to be supplied to a laser diode in accordance with an input signal representative of a laser beam power varying depending on a relative speed between a magneto-optical disk and a spot of a laser beam emitted by the laser diode on the optical disk. The driver circuit has a non-linear first operation range and a substantially linear second operation range subsequent to the first operation range. For a linear operation of the driver circuit, a level shifter circuit is connected to the driver circuit for applying a shift voltage to the driver circuit with a result that an excess output current is produced by the driver circuit even when the input signal is non-existent.

Abstract: The gain coupled distributed feedback semiconductor laser includes an active layer and a diffraction grating which is provided in the vicinity of the active layer and has a plurality of light absorption layer periodically arranged along a resonator length direction. A relationship among energy h.nu. (h is Planck's constant, and .nu. is a frequency of induced emission light), forbidden band width E.sub.g of the light absorption layer, and energy band width .delta.E where free electrons are thermally distributed satisfies h.nu..gtoreq.E.sub.g +.delta.E.

Abstract: The present invention relates to a laser generator in which a laser beam is generated by energizing a laser medium and is amplified optically with optically amplifying mirrors, and the laser beam is received by a absorber, wherein a spacer 9 having a through hole 9a for passing therethrough the laser beam and at least one small second through hole 9b is arranged at a circumference of an absorber 7, and a cooling medium 12 circulates in the small second through hole 9b of the spacer 9. In this structure, if a scattering laser beam is generated at the circumference of the laser beam absorber, a parallelism of the optical amplifying mirrors is maintained so that the laser generator can generate the stable laser beam.

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: A surface emission type semiconductor laser having an optical detector which can satisfactorily assure both the laser emission characteristics of the photoemitter and the optical-to-electrical conversion efficiency. The laser comprises a first conducting semiconductor layer and a second conducting semiconductor layer formed on first and second regions of a semiconductor substrate. Over the second conducting semiconductor layer on the first region is formed an optical resonator which emits light perpendicular to the plane of the semiconductor substrate. On the second region, at least one photodiode is formed by the first and second conducting semiconductor layers. On the first region the second conducting semiconductor layer is formed with a thickness of at least 1 .mu.m, and is used as a lower electrode for supplying a current to the optical resonator. On the second region, the second conducting semiconductor layer forming the at least one photodiode is formed with a thickness of less than 1 .mu.

Abstract: New sensing and diagnostic methods are implemented with multimode fiber Bragg gratings (MMFBG) and methods for sensor addressing and multiplexing are described. Real time structural strain and vibration monitoring using optical time domain reflectometry (OTDR) is discussed. The first all-mode, wave optics calculations of the reflectivity of Bragg gratings in highly multimode optical fibers are presented, including the effects of individual mode power changes due to microbending transducer loss upstream from the grating. Two categories of multimode fiber gratings are possible, independent mode and mode coupling, and the fabrication differences between these types of gratings are described. The reflectivity properties of independent mode multimode fiber gratings are examined and compared to single mode fiber gratings.

Abstract: An optical end-pumped fiber laser doped with one or more rare-earths and with distributed feedback (DFB) via a fiber Bragg-grating, which is oscillating on two orthogonally polarized wavelengths. The distance between the wavelengths may be tuned by changing the birefringence of the fiber. The laser may be applied as a polarimetric sensor in which an asymmetrical force changes the wavelength separation, or as a tunable two-wavelength source. A particular preferred field of application is for measuring the pressure in pipes, to determine the flow.

Abstract: A semiconductor laser which does not cause a sudden failure due to an electric surge. A ridge that is formed by a GaAs buffer layer, an n-InGaP cladding layer which is lattice-matched to a GaAs substrate, a strained-quantum well active layer, a p-InGaP cladding layer which is lattice-matched to the GaAs substrate, a p-GaAs waveguide layer, a p-InGaP cladding layer which is lattice-matched to the GaAs substrate, and a p-GaAs cap layer is constructed on the n-GaAs substrate by being buried therein by an n-InGaP current-blocking layer. A device stripe is constructed by a current-injected region in the device and current-non-injected regions near facets.

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 crystal substrate, with an adhesive uniformly applied to its entire rear surface, is fixed to the inner wall of an element housing. By adjusting the thickness of a wall of the element housing, forming grooves in the wall, or fixedly attaching a deadweight to the wall, the resonant frequency of the element housing is adjusted so as to restrain the optical waveguide element from resonating. Further, by mounting the optical waveguide device on a printed board via an elastic member or the like, propagation of the vibration to it is suppressed.

Abstract: A desktop medical laser generator (10) for laser surgery has a base plate (12) and an optical assembly (14) mounted thereon. The optical assembly (14) has an improved lamp housing (16) having two identical shell sections (44) and associated components for housing a YAG rod (60) and a lamp (58). Light emitted from the lamp housing (16) is doubled in frequency by a KTP crystal (26), monitored by two power detectors (32,34) and emitted through an output connector (36). A line power control system (90) insures the current drawn from a standard wall receptacle (80) does not exceed accepted limits. An output power detection system (90) closely monitors output power.

Abstract: A diode-pumped high performance solid state laser has at least one pump module comprising at least two laser diode arrays which transversely irradiate a solid state laser rod. The path length of the radiation emitted by a laser diode array through the solid state laser rod and the required absorption path for this radiation, determined by the emission wavelength of this radiation and the doping of the laser-active medium, are adapted to one another extensively in different ways.

Abstract: A VCSEL 101 comprising an optical cavity having an optical loss and a loss-determining element 117 coupled to the optical cavity. The loss-determining element 117 progressively increases the optical loss of the optical cavity with increasing lateral distance from the optical axis 105. The optical cavity includes a first mirror region 111, a second mirror region 107, a plane light-generating region 125 sandwiched between the first mirror region 111 and the second mirror region 107, perpendicular to the optical axis 105, and an element 113 that defines the lateral extent of the optical cavity in the plane of the light-generating region 125. The first mirror region 111 and the second mirror region 107 are both conductive and have opposite conductivity modes.

Abstract: A wavelength tunable laser emission component includes on the same substrate an active emission section and a Bragg section that includes a waveguide in which is formed a plurality of individual Bragg gratings corresponding to particular Bragg wavelengths. The waveguide has an electro-absorbent structure, the subsections of the Bragg section each being voltage-controlled. The laser emission wavelength is tuned to one or other of the Bragg wavelengths of these subsections according to control voltages applied thereto.

Abstract: A method and apparatus for curved-angle cleaving of optical fibers is presented. The method requires the introduction of a flaw in an optical fiber to be cleaved, and the application of predetermined stress and strain to the optical fiber in the vicinity of the flaw to cause curved-angle cleaving of the optical fiber at the flaw. More particularly, one embodiment of the method requires fixing first and second portions of the optical fiber, for example, by clamping, and introducing a flaw into the optical fiber between the first and second portions. Then, a substantially concentrated force is applied to the optical fiber between the flaw and the first portion of the optical fiber, on a side of the optical fiber opposite the flaw, in order to cause the optical fiber to cleave with a curved-angle cleave. Another embodiment of the method applies a substantially concentrated force to the fiber before introduction of the flaw.

Abstract: A first stack (112) of distributed Bragg reflectors, a first cladding region (114) disposed on the first stack of distributed Bragg reflectors (112) and including a defect inhibition layer (117) an active area (122) disposed on the first cladding region (114), a second cladding region (132) disposed on the active area (122) and including a defective inhibition layer (136), and a second stack (140) of distributed Bragg reflectors disposed on the second cladding region (132). The defect inhibition layers (117, 136) substantially prevent defects in the active area (122).

Abstract: A pulsation laser includes an n-type AlGaAs cladding layer on an n-type GaAs substrate, three quantum well active layers having central increased thickness regions and disposed on the cladding layer, and a p-type AlGaAs cladding layer disposed on the quantum well active layer. The increased thickness region of the active layer is not more than one-quarter of the length of the resonator of the laser.

Abstract: A compact WDM optical device can demultiplex an optical laser signal containing several different wavelengths corresponding to particular channels, and, in reverse operation operate as a multiplexer to interleave several different wavelengths into a multiplexed multi-channel optical laser signal with improved insertion loss characteristics. The optical device includes a linear array of passive resonant optical cavities, in the form of Fabry-Perot filters, extending in a lateral direction and an integral array of associated microlenses extending in the lateral direction. Each microlens has a center which is offset from the central longitudinal axis of an associated Fabry-Perot filter to reflect laser radiation through the device. Each optical cavity is tuned by adjusting the longitudinal dimension thereof to a particular wavelength contained in the multi-channel optical signal. A stepped-wavelength steered laser radiation source for the optical device uses a VCSEL array with offset microlenses.