Abstract: A workpiece is irradiated by a laser beam scanned in an oscillating track as the workpiece is advanced along a feed path in a hardening process. Sinusoidal variations in scan velocity are offset by decreasing the laser beam power level at phases in the scanning cycles corresponding to high and low scan displacement peaks, where the scan velocity is least. The beam power is increased near the scanning center line where the scan velocity is highest. The beam energy applied per unit of area is thus equalized over the scanning cycle. The workpiece temperature can be sampled at regular phases by a non-contact temperature sensor in the optical path, and used to control beam power versus phase in a subsequent scanning cycle. Alternatively or in addition, a sinusoidal beam power pattern can be stored and used to offset scan velocity variations as a function of phase.

Abstract: Quantum cascade laser especially comprising a gain region (14) formed from several layers (20) which each comprise: alternating strata of a first type (26) each defining a quantum barrier made of AlInAs and strata of a second type (28) each defining a quantum well made of InGaAs, and injection barriers (22), interposed between two of the layers (20). The layers of the gain region (14) each constitute an active region extending from one to the other of the injection barriers (22) which are adjacent to it. The strata (26, 28) are dimensioned such that: each of the wells comprises, in the presence of an electric field, at least a first upper subband, a second middle subband and a third lower subband and that the probability of an electron being present in the first subband is highest in the vicinity of one of the adjacent barriers, in the second subband in the middle part of the region and in the third subband in the vicinity of the other of the adjacent barriers.

Abstract: Plate springs as coupling members can absorb deformation of an oscillator case due to heat and do not transmit the deformation to two optical bases constituting an optical resonator, and it is thereby possible to maintain an appropriate positional relation between the optical cases. A harmful deformation force is produced due to imperfect alignment deformation of bellows each of which is connected between the oscillator case and each optical base. The plate springs can also suppress the force acting on the two optical bases, and it is thereby possible to keep a laser optical axis of a laser beam to be a fixed position.

Abstract: An electronic device such as a laser diode is mounted on a heatsink assembly within a TO-can package. The heatsink assembly is mounted in heat exchange relation with a heat pipe by being on or adjacent a heat pipe. The heat pipe is either attached to an exterior face of the TO-can package or passes into the TO-can package to efficiently draw heat away from the heatsink assembly.

Abstract: A source of pulses of coherent radiation at a wavelength of approximately 1 ?m, comprises a pump source for producing pump light, a laser cavity comprising an Yb3+-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Abstract: A tunable optical local oscillator is used for optical heterodyne signal detection using an electrooptic Mach-Zehnder modulator to produce a rapidly tunable optical signal from a tunable RF frequency generator. A combination of the Mach-Zehnder modulator and optical fibers for providing stimulated Brillouin scattering are used to suppress unwanted signals for providing a spectrally pure optical local oscillator waveform. Suppression of unwanted optical signals, up to 50 dB, generated by the Mach-Zehnder modulator is obtained, resulting in high spectral purity of the optical local oscillator waveform with an extended tuning range of the tunable optical oscillator equal to the operating bandwidth of up to 60 GHz of the Mach-Zehnder modulators.

Abstract: A Raman gain control method of controlling a Raman gain caused by simultaneous application of pump lights of a plurality of wavelengths to an optical fiber, which includes, based on a relation of a ratio coefficient which is a ratio of power of each pump light to total power of all the pump lights with the Raman gain, from a designated value of the Raman gain, calculating power of each pump light realizing the designated Raman gain within a designated wavelength range, and controlling power of each pump light applied to the optical fiber to apply each pump light at each power calculated.

Abstract: A semiconductor laser stack apparatus 1 comprises three semiconductor lasers 2a to 2c, two copper plates 3a and 3b, two lead plates 4a and 4b, a supply tube 5, a discharge tube 6, four insulating members 7a to 7d, and three heat sinks 10a to 10c. Here, the heat sink 10a to 10c is formed by a lower planar member 12 formed with a supply water path groove portion 22, an intermediate planar member 14 formed with a plurality of water guiding holes 38, and an upper planar member 16 formed with a discharge water path groove portion 30 which are successively stacked one upon another, whereas their contact surfaces are joined together. The heat sink 10a to 10c is provided with pillar pieces 24 for connecting the bottom face of supply water path groove portion 22 and the lower face of intermediate planar member 14 to each other, and pillar pieces 32 for connecting the bottom face of discharge water path groove portion 30 and the upper face of intermediate planar member 14 to each other.

Abstract: A wavelength tunable laser comprising a laser diode and a closed external cavity formed by one or more optical resonators either horizontally or vertically coupled to adjacent waveguides. The optical resonator primarily functions as a wavelength selector and may be in the form of disk, ring or other closed cavity geometries. The emission from one end of the laser diode is coupled into the first waveguide using optical lens or butt-joint method and transferred to the second waveguide through evanescent coupling between the waveguides and optical resonator. A mirror system or high reflection coating at the end of the second waveguide reflects the light backwards into the system resulting in a closed optical cavity. Lasing can be achieved when the optical gain overcomes the optical loss in this closed cavity for a certain resonance wavelength which is tunable by changing the resonance condition of the optical resonator through reversed biased voltage or current injection.

Abstract: An improved optical communication system is provided, the system particularly suited for so-called short-haul applications, e.g., applications involving transmission over distances less than 100 km, such as metro applications. The system uses an external cavity laser made up of a gain medium that comprises an active region, a beam expanding region, and an antireflective layer, an optical waveguide located adjacent the gain medium, and a Bragg grating integral with or coupled to the optical waveguide. The medium and the optical waveguide, due to the beam expanding region, exhibit a coupling efficiency of at least 40%, advantageously at least 50%, even in the absence of coupling optics, and the laser is configured and operated to emit at least two modes.

Abstract: The invention pertains to wavelength-agile optical filters suitable for wavelength-division-multiplexed (WDM) optical communications networks. More particularly, the invention pertains to optical filters with a wavelength reference that can be remotely switched to arbitrarily selectable channels on a standard grid, and to re-configurable optical communications networks employing same. The present invention provides a communication apparatus with a tunable filter which may be used in a wide range of applications including tuning an external cavity laser (ECL), selecting a wavelength for an add/drop multiplexer and providing channel selection and feedback for a wavelength locker. The filter may be utilized as a discrete component or in combination with circulators, wavelength lockers and gain medium. The filter may be implemented in whole or in part as part of a gain medium.

Abstract: A semiconductor laser module includes: a semiconductor laser element which emits laser light; a waveguide-type optical wavelength selection element which includes an optical waveguide, and selects a first portion of the laser light having a predetermined wavelength; and an optical wavelength conversion element which converts a second portion of the laser light having the predetermined wavelength to wavelength-converted laser light having a converted wavelength. The semiconductor laser element, the waveguide-type optical wavelength selection element, and the optical wavelength conversion element are coupled. The semiconductor laser element contains a multiple-quantum-well active layer including a plurality of quantum-well sublayers, where one of the plurality of quantum-well sublayers is different from another of the plurality of quantum-well sublayers in thickness and/or composition.

Abstract: High powered lasers of substantially any wavelength produced by certain processes including the process of providing a structure comprising a substrate with an epi structure thereon comprising a gain region with multiple quantum wells, a mirror stack coupled to the gain region, and a conductive layer coupled to the mirror stack; dividing the conductive layer into a conductive, central area and one or more dielectric, peripheral areas; attaching a conductive plate to the conductive layer; thinning the substrate to improve the passage of light therethrough to produce a substrate remnant; and attaching an electrode to the substrate remnant.

Abstract: A bottom emitting VCSEL where the light emitted can be monitored without obstruction. No additional mountings are required, such as a header, to monitor output, which mountings are necessary in prior art arrangements.

Abstract: The invention pertains to wavelength-agile optical filters suitable for wavelength-division-multiplexed (WDM) optical communications networks. More particularly, the invention pertains to optical filters with a wavelength reference that can be remotely switched to arbitrarily selectable channels on a standard grid, and to re-configurable optical communications networks employing same. The present invention provides a communication apparatus with a tunable filter which may be used in a wide range of applications including tuning an external cavity laser (ECL), selecting a wavelength for an add/drop multiplexer and providing channel selection and feedback for a wavelength locker. The filter may be utilized as a discrete component or in combination with circulators, wavelength lockers and gain medium. The filter may be implemented in whole or in part as part of a gain medium.

Abstract: A nitride semiconductor laser device includes a first-conductivity-type cladding layer formed of a nitride semiconductor material; an active layer formed of a nitride semiconductor material; and a second-conductivity-type cladding layer formed of a nitride semiconductor material. The first-conductivity-type cladding layer has a first main surface and a second main surface, the first main surfaces being closer to the active layer from the second main surface, and includes a first-conductivity-type first cladding layer and a first-conductivity-type second cladding layer having a different composition from that of the first-conductivity-type first cladding layer, which are provided in this order from the first main surface. The first-conductivity-type first cladding layer has a refractive index lower than that of the first-conductivity-type second cladding layer.

Abstract: A laser used in a DWDM optical-fiber application is controlled so that, before it is powered up or down, its output power is maximally attenuated, the result being minimal cross-channel interference due to out-of-spec. wavelength. Laser control is further characterized by the steps of: (a) with laser current at zero, establishing a desired temperature of operation of the laser; (b) with output attenuation at maximum, increasing the current and regulating it to a level at which the design operating wavelength is achieved, and (c) decreasing the attenuation until the desired output power to the optical-fiber link is attained. Maximum attenuation is preferably applied during step (a).

Abstract: A semiconductor laser includes a substrate; and a multilayered film formed on the substrate and including an active layer. The multilayered film includes a stripe structure that extends in a longitudinal direction of a resonator and has a tapered portion in which a width of a stripe changes in a tapered manner; and a first side face and a second side face that sandwich the stripe structure. At least one side face of the first side face and the second side face is inclined with respect to a principal surface of the substrate.

Abstract: A method of stabilizing output characteristics of an SLD device with respect to ambient temperature is disclosed. The SLD device includes a cooling module for cooling an SLD chip, and a sensor for providing a set point signal corresponding to a set point temperature. The cooling module and the sensor, together with control electronics, form a feedback loop for maintaining the set point temperature within a predetermined range. The method comprises determining a variation of the output characteristics as a function of ambient temperature, and determining a variation of the set point signal as a function of ambient temperature, wherein the variation of the set point signal corresponds to the variation of the output characteristics. The method also includes modifying the feedback loop so as to offset the variation of the set point signal, and thereby stabilize the variation of the output characteristics as a function of ambient temperature.

Abstract: A device for producing laser radiation having a wavelength of about 2 ?m, the device comprising: a solid-state sample capable of producing lasing transitions corresponding to a wavelength of about 2 ?m; and a source of pumping radiation having a wavelength of about 1 ?m, the source being arranged so that at least some of the radiation produced thereby is absorbed by the solid-state sample, causing the solid-state sample to emit radiation having a wavelength of about 2 ?m.