Abstract: A laser system wherein, in order that a high-output and high-quality single mode of a cross sectional area larger than the beam diameter determined by the construction of a resonator can be obtained stably, although this has heretofore been impossible, there is used a coupling mirror provided with a partial reflection film and an antireflecting film, a laser beam mode is selected using the partial reflection film, a phase difference between laser beam portions caused by a difference in construction between the partial reflection film and the antireflecting film is compensated using a phase difference compensating apparatus, and there is formed an aperture whose diameter is set to a value of not larger than four times the diameter of the partial reflection film.

Abstract: A diode pumped laser system includes a laser cavity with an active laser medium. A laser diode, with an emitter region having an output facet that produces light at a frequency .lambda..sub.1, is the pump source for the laser medium. A coupling optics is positioned on an emission path of radiation from the emitter region and is optically coupled and spaced from the diode. The coupling optics produces stray radiation. An optical fiber, with a first end and a second end, is included. The first end of the fiber is oriented with respect to the coupling optics such that radiation from the emitter region is optically coupled into the optical fiber. The second end of the fiber is coupled to the laser cavity. A detector is positioned in a spaced, adjacent relationship to the coupling optics along an emission path of the stray radiation. The detector detects at least a portion of the stray radiation and produces a detected output in response to the stray radiation.

Abstract: A system is disclosed for minimizing the depolarization of a laser beam due to thermally induced birefringence in a rod-shaped gain medium over a wide range of excitation levels. After passing through the gain medium, the polarization of the beam is rotated by ninety degrees and either redirected back into the same gain medium or a substantially identical gain medium. By this arrangement, the portion of the beam that was radially polarized during the first pass is tangentially polarized during the second pass so that the original polarization is restored. In order to maximize the compensation, a relay image system is used to generate an image of the beam in the gain medium as it existed during the first pass and project that image into the gain medium during the second pass. The magnification of the relayed image is substantially one to one with respect to the actual image.

Abstract: A rod lens or a cylindrical lens is disposed in front of a semiconductor laser to increase a divergence angle of a laser beam emitted from the semiconductor laser so as to form a substantially circular far field pattern. In another constitution, there is disposed in front of a semiconductor laser a composite lens having two cylindrical surfaces whose cylindrical axes are perpendicular to each other. The cylindrical surface on the side of the semiconductor laser is a convex surface and the other cylindrical surface is a convex or concave surface. In still another constitution, two semiconductor lasers emitting the same optical signal are arranged adjacent each other so that respective light emitting portions of two pn junction planes are located in the same plane and perpendicular to each other, and that laser beams form orthogonal spots at a single predetermined position.

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 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: A laser resonant cavity for utilizing media, having an annular cross sect as well as two end mirrors. The end mirrors exhibit a toroidal surface, and at least one end mirror has at least one aperture through which the laser beam can be coupled out.

Abstract: A phase shift device for a laser beam has a circular first area transparent so the laser beam and a second area provided around the first area and transparent to the laser beam. The first and second areas generate a phase difference for example 180.degree. in the passing light beams. The phase shift device is positioned for example at a beam waist of a laser scanning apparatus to form a beam spot of a diameter smaller than that defined by the numerical aperture of the imaging optical system. Structure of a laser apparatus employing such phase shift device is also disclosed.

Abstract: A ring laser is described, which has a ring (1) in which laser radiation is generated. A coupler (4) couples a part of the radiation in the form of two waves (7,8) to two waveguides (5,6). A combiner (11) combines the two waves to an output wave (12) in an output waveguide (13). By providing a reflector (16) in the output waveguide, a part of the output wave is reflected to the ring via the combiner, the two waveguides and the coupler. The radiation waves travelling in the ring couple to the reflected wave and thereby acquire a well-defined phase difference. The resultant phase equality of the two waves (7,8) at the input of the combiner ensures that the powers of the waves are added in phase so that the ring laser supplies the maximum possible power.

Abstract: An optical device includes a semiconductor optical amplifier and a lens for receiving optical energy from the optical amplifier. The lens and the optical amplifier are monolithically integrated on a common substrate. The optical amplifier may be of the type having a tapered active region. Rather than an optical amplifier, a semiconductor laser may be integrated with the lens. The lens may be formed by changing the refractive index of the waveguide core which is formed in the semiconductor material. This refractive index change may be produced by changing the thickness of a portion of the waveguide core layer.

Abstract: Method for making a custom phase-conjugating diffractive mirror for a laser resonator comprising the steps of: (a) (a) choosing a specified beam mode profile a.sub.i (x,y) that will suit need of said designer, (b) calculating the mode profile b(x',y') which is a value of the specified a.sub.i (x,y) that is propagated to the reflection surface of the diffractive mirror and (c) calculating mirror reflectance t(x',y') which reflects phase conjugate of b(x',y'). A method for fabricating such a mirror is shown. Another aspect of the invention is the addition of a phase adjusting element into a laser resonator, and compensating for the addition of a phase adjusting element in the design of other phase-adjusting elements such as the mirrors.

Abstract: A short-wavelength laser light source having a semiconductor laser for emitting laser light is provided. The light source includes a power supply for driving the semiconductor laser and thereby causing the semiconductor laser to emit a fundamental wave, a polarization inversion-type light-wavelength converting device for generating from the fundamental wave a harmonic wave having a shorter wavelength than the fundamental wave; and laser light feedback means for feeding light of the fundamental wave lying in a selected wavelength region back to the semiconductor laser, thereby achieving oscillation wavelength locking. Said power supply supplies to the semiconductor laser a high-frequency power containing AC components oscillating in a cycle short enough to cause the semiconductor laser to emit the fundamental wave in the form of pulsed laser light.

Abstract: A laser module includes a hollow, cylindrical casing having a tapered laser beam emitting hole at one end and a lens holder coupling portion at an opposite end, a lens holder having one end fitted into the lens holder coupling portion and an opposite end made with an inner thread, a lens mounted inside the casing and retained between a cushion ring and the lens holder; a focus adjustment socket having one end made with an outer thread threaded into the inner thread of the lens holder and an opposite end sealed with a locating cap; a control circuit board fastened to the locating cap and disposed inside the focus adjustment cap to carry a laser diode chip and a photo detector and controlled to drive the laser diode chip to emit a constant laser beam out of the casing through the lens.

Abstract: Disclosed is a non-linear optical device in which the non-linear medium comprises a circular surface on which the light beam to be processed gets reflected. A structure such as this can be used to resolve the difficulties of making mirrors of the cavity containing the non-linear medium.

Abstract: A solid-state laser for generating harmonic laser light substantially at a desired wavelength has a pump diode body made of a first material, which is preferably aluminum, having a first coefficient of expansion and a laser diode mounted in the pump diode body for generating pump energy. A laser body assembly, which is positioned on the pump diode body, is made of a second material, which is preferably steel, having a second coefficient of expansion. The first and second coefficients of expansion of the respective pump diode body and the laser body assembly have a known relationship such that the laser cavity expands and contracts at a particular rate as the temperature of the laser increases and decreases to provide a substantially constant generation of the harmonic laser light. A laser gain chip mounted on an entrance mirror, which forms the back end of a laser cavity, generates fundamental laser light in response to pump energy from the laser diode.

Abstract: A microcavity semiconductor laser disclosed therein includes a double-heterostructure section including an intermediate active layer sandwiched between a first or lower cladding layer and a second or upper cladding layer above a semiconductive substrate. A first multi-layered reflector section is arranged between the substrate and the double-heterostructure section to have its reflectance which becomes maximum near the oscillation wavelength of the laser. The upper cladding layer is semi-spherically formed. A three-dimensional optical reflector covers the double-heterostructure section, for controlling spontaneous emission obtained in the double-heterostructure section along various directions, and for increasing the coupling ratio of spontaneous emission with a specific laser mode, thereby to decrease the threshold current.

Abstract: A ring laser gyroscope detector lens system for mounting on a ring laser gyroscope body having a resonant cavity. The ring laser gyroscope body has CW and CCW counterpropagating light beams propagating in a plane normal to the rate input axis of the ring laser gyroscope. The ring laser gyroscope detector lens system comprises a means for extracting a component of each of the CW and a CCW light beams from the cavity and for providing extracted CW and CCW beams. A means for combining the extracted CW and CCW beams to form an interference light source receives the extracted light. A planar array of detector element receives light from an objective lens means responsive to the interference light source. The objective lens means is typically a cylindrical lens that forms an interference light source pattern on the planar array of detector elements. A bias and amplification means is provided for conditioning each of the detectors in the array to be independently responsive to incident light intensity.

Abstract: A hollow member or an envelope 7 housing a laser medium 3 having a reflective coating 31 on one surface thereof, a non-linear optical crystal 4 and an output mirror 5 having a reflective coating 51 on one surface thereof has a thin-walled portion 71 in its center portion. The air-tightly sealed envelope 7 is evacuated through an exhausting pipe 9 and, after sealing the pipe 9, a laser resonator unit 70 is obtained. By arranging a laser diode unit 10 on the reflective coating 31 of the laser medium 3 and integrating it by a connecting member 17, a long life-time, compact solid state laser excited by laser diode is obtained.

Abstract: The invention relates to a semiconductor diode laser whose strip-shaped active region is limited by an end face which is curved for forming a lens of a given strength. A disadvantage of the known diode is that it has a comparatively high starting current. This is found to be caused inter alia by the etching necessary for forming a curved end face. During etching, unevennesses arise in the curved end face where scattering of the generated radiation occurs. This increases the starting current of the diode. A diode according to the invention is characterized in that the curved end face is covered with a covering layer of a material having a refractive index different from that of the active layer, and the refractive index of the covering layer and the curvature of the end face are so chosen that the scattering of the generated radiation is a minimum for the given strength of the lens.

Abstract: A laser resonator includes; an optical oscillator including a discharge tube, and a pair of reflecting mirrors arranged at both ends of the discharge tube while inner surfaces of the mirrors confront each other; electrodes confronting each other with the discharge tube held therebetween; a gas pipe connected to the optical oscillator, and a gas circulating device connected to the gas pipe for circulating laser gas, wherein the laser resonator generates laser light when a voltage impressed to the electrodes invites discharge of the discharge tube while laser gas is circulated in the discharge tube by the gas circulating device.

Abstract: An intracavity frequency-doubled solid-state laser uses a Nd:GdVO.sub.4 laser gain chip to generate a beam of visible laser light which may have wavelengths substantially in the green portion of the optical spectrum. A back end of the laser cavity is defined by an entrance mirror while a front end of the laser cavity is defined by a mirrored surface. A laser diode generates pump light which is transmitted through the entrance mirror into the laser gain chip. The laser gain chip, which may be immediately adjacent the entrance mirror, emits fundamental laser light having a wavelength of approximately 1063 nm in response to the pump light. A frequency doubler chip positioned immediately adjacent the laser gain chip doubles the frequency of the fundamental laser light to produce harmonic laser light having a wavelength of substantially 532 nm.

Abstract: An apparatus confocally delivers to an object an infrared CO.sub.2 laser beam and a highly visible (e.g., blue-green) aiming beam. The beams from the two lasers are coaxially superimposed by means of a plate which transmits visible light and reflects infrared light. The resulting two coaxial beams are then guided to the object by means of reflective surfaces. Reflective beam guidance provides coincident focus of the infrared and aiming beams with unprecedented precision and also permits the combination of an infrared beam with a highly visible aiming beam.

Abstract: A laser oscillator which is capable of providing a circularly polarized laser beam by an external optical system having a brief configuration. A folding section of a folded-type resonator (10) comprises reflecting mirrors (4a), (4b) and (4c). The reflecting mirror (4a) is inclined at an angle of 45.degree. to an optical axis of an excitation section (3a), and the reflecting mirror (4c) is inclined at an angle of 45.degree. to an optical axis of an excitation section (3b). The reflecting mirror (4b) is horizontally arranged so that the center of the mirror is positioned at the vertex of an isosceles right triangle with respect to the reflecting mirrors (4a) and (4c). Thus, an S polarized-light component of a laser beam from the excitation section (3b) is reflected by the reflecting mirror (4c) toward the reflecting mirror (4b).

Abstract: A laser beam light source device which has Fresnel lens having grating of unequal spacing and facing a laser diode, and condenser lens made of resin. The focal length of the condenser lens is set at a value which nullifies changes in the focal length of the Fresnel lens induced by fluctuations in the oscillation wavelength of the laser diode accompanying temperature change, and changes in the focal length of the Fresnel lens accompanying temperature change. Further a laser beam scanning optical system for scanning on a scan line via a deflecting device and optical elements by a laser beam emitted from a laser light source based on image information. In the laser scanning optical system, a pair of anamorphic lenses are disposed anteriorly and posteriorly to the deflecting device to correct surface tilt of the deflecting device, one of the anamorphic lens being a Fresnel lens, another of the anamorphic lens being made of resin.

Abstract: In adjusting the optical axes of a semiconductor laser and an optical system for directing a laser beam emitted by the semiconductor laser, with a system including a plate having an opening and being shiftable parallel to a light receiving surface, and a holder being rotatable while being fitted in the opening, a point image having an excellent characteristic is formed at a predetermined position of the light receiving surface even if the optical axis of the semiconductor laser or the optical axis of the optical system inclines.

Abstract: A narrow band excimer laser and a wavelength detecting apparatus are suitable for use as a light source of a reduction projection aligner of a semiconductor device manufacturing apparatus. In the excimer laser, the ruling direction and the beam expanding direction of a prism beam expander are made substantially coincide with each other, and a polarizing element causing selective oscillation of a linearly polarized light wave substantially parallel with the beam spreading direction of a prism beam expander is contained in a laser cavity. A window at the front or rear side of a laser chamber is disposed such that the window make a Brewster's angle with respect to the axis of the laser beam in a plane containing the beam expanding direction of the prism expander and the laser beam axis.

Abstract: A tunable laser formed on a semiconductive wafer comprising a plurality of monolithically integrated optical amplifiers and a planar optical multiplexer is disclosed. According to the invention, one of the optical amplifiers is activated by energy, which amplifier produces a signal. The signal is carried along a waveguide associated with the optical amplifier and enters a reflective Dragone router, which is the preferred optical multiplexer. The reflective Dragone router functions, in conjunction with the activated optical amplifier, to define a wavelength selective optically transmissive pathway to create lasing action. Facet mirrors are cleaved in the semiconductive wafer defining the lasing cavity which includes the optical amplifiers, associated waveguides and the reflective Dragone router.

Abstract: A laser module includes a hollow, cylindrical casing having a tapered laser beam emitting hole at one end and an inner thread at an opposite end; a lens mounted inside the casing and retained between a cushion ring and a locating ring; a base having an outer thread threaded into the inner thread on the casing; a laser diode chip and a photo detector mounted on the base and connected to contact pins of the base; a control circuit board fitted into the rear open end of the casing to block the base on the inside and electrically connected to the contact pins on the base for controlling the laser diode chip to emit a constant laser beam out of the tapered laser beam emitting hole via the lens.

Abstract: A room-temperature solid state laser for producing an output laser emission t any wavelength within a preselected range of wavelengths is disclosed.

Abstract: An apparatus and method for controlling the propagation path of a light beam are disclosed. A lens material having a temperature-dependent index of refraction is positioned in the path of the light beam. A heat source is disposed on one face of the lens material and a heat sink is disposed on the opposite face. A controller regulates the distribution of heat to the heat source and the extraction of heat from the heat sink so that a temperature gradient is formed within the lens material. The temperature gradient creates a refractive-index gradient in the lens material, causing a thermal lensing effect. The device may be used in a laser cavity for controlling laser-beam divergence caused by pump-induced thermal lensing in the gain medium.

Abstract: An excimer laser ablation processing for forming via holes in a resin film by irradiation of an excimer laser wherein, the emission of light caused during the decomposition of the resin during the processing is detected, its intensity is measured, and the endpoint of the processing is judged or a comparison is made of the positions of light emission and the design positions for processing to examine for the presence of defects. Provision is made of a means for measuring the intensity and a means for judging the endpoint of the processing from the changes in the intensity of light emission during the processing.

Abstract: A slab laser amplifier array includes a plurality of parallel, stacked, laser resonators, with each resonator having a walk-off mode of propagation of laser light from an input side of the resonator to an output side of the resonator where the exiting light diffracts around the resonator mirror. A source of a plurality of phase related, for example co-phasal, light beams supplies phase related light to each input side. The source of phase related light may be a source of one single mode beam followed by a telescope with an aperture having plural stops or a co-phasal array of laser resonators. A laser array of open resonators also has circular concentric electrodes.

Abstract: Producing high efficiency laser wave mixing and laser harmonic generation laser beams by reconstruction of fundamental and second harmonic laser beams from a frequency doubling crystal by use of a pair of optical wedges. The optical wedges are positioned with their angled surfaces facing each other with substantially 180 degrees of relative rotation and separated at a predetermined distance. The two spaced apart laser beams enter the first optical wedge from the frequency doubling crystal and the two beams converge after exit the first wedge. The converged laser beams enter the second wedge and exit therefrom, forming a coaxially overlapping single beam which is to be used for high efficiency generation of a higher order harmonic laser beam.

Abstract: A laser diode unit, having advantages of dissipating heat quickly, being capable of protecting itself from being destroyed by an incidental electrostatic or electric voltage, being effective to deal with the operations of aligning, positioning, adjusting, and being easy to be mass-produced. The laser diode unit includes a laser diode element for emitting laser light beam; a mold housing for securing the laser diode element thereon, laser light beams emitting from the laser diode element being capable of penetrating the mold housing; a collimating lens set disposed within the mold housing for collimating the light of the laser beam emitting from the laser diode element; and an adjusting means for driving the collimating lens set to move to and fro within a through bore formed in the mold housing.

Abstract: A Q-switched laser having a gain medium disposed within a first resonant cavity and a second resonant cavity, sharing a common mirror with the first cavity, whose optical length is adjustable such that the quality Q of the first resonant cavity is affected. One aspect of the invention is the selection of the cavity lengths and the reflectivities of the mirrors of the first and second cavity such that Q-switched pulses of less than 100-ps duration can be obtained. Another aspect of the invention is the ability to generate said pulses with peak powers in excess of 100 kW for applications in high-precision optical radar, nonlinear optics, micromachining, microsurgery, and other applications where short pulses with high peak powers are required.

Abstract: A laser beam dividing apparatus (10) having a first beam splitter (14) with an aperture (16) therein positioned in the path of a laser beam (12) such that a portion of the laser beam (12) passes through the aperture (16) onto a second beam splitter (20) and a portion of the laser beam (12) impinges upon the first beam splitter (14). Both the first beam splitter (14) and the second beam splitter (20) are, optionally, made from a dichroic material such that a green component (24) of the laser beam (12) is reflected therefrom and a yellow component (26) is refracted therethrough. The first beam splitter (14) and the second beam splitter (20) further each have a plurality of facets (22) such that the components (24, 26) are reflected and refracted in a number equaling the number of facets (22).

Abstract: Light emitted from the rear facet of an injection laser diode chip is focused to a compact spot size at the photosensitive surface of a photodiode responsive to a laser bit rate of 2.5 Gbit/s by means of a substantially ellipsoidal reflector.

Abstract: In order to improve an apparatus for removing material from a target, comprising a high-power laser generating laser pulses with a pulse duration in the picosecond range and comprising a resonator, in which a mode-locking device and a Q-switch are arranged, a frequency multiplier following the high-power laser and a beam guide for focusing the laser beam coming from the frequency multiplier onto the target, such that the energy in the single laser pulses having a pulse duration in the picosecond range is as high as possible, it is suggested that the resonator have fully reflecting end mirrors for generating single high-energy laser pulses, that a system for the controlled coupling out of single pulses be arranged in the resonator and that a control be provided for coupling out a single pulse following release of the laser activity by the Q-switch and the build up of the single pulse after repeated round trips through the resonator.

Abstract: A laser resonator is provided for producing a radially polarized laser beam. The laser resonator includes an active laser medium disposed between a highly reflective end mirror and an opposing partial transmission mirror which define a laser resonator cavity therebetween for producing oscillating optical radiation. A conical Brewster window is further located within the laser resonator cavity and has an optically transparent medium oriented in accordance with the polarizing (i.e., Brewster) angle. As the optical radiation oscillates within the resonator cavity, the conical Brewster window causes the radiation transmitted therethrough to have a radial polarization. Accordingly, the laser resonator produces a laser output which has a radially polarized electric field associated therewith.

Abstract: An optical apparatus (23) for emitting light is constituted by a fixation holder (8) fixed to a predetermined positioning fixation jig via a fixation plate (8a), a lens-barrel (10), fitted on a cylindrical portion of the fixation holder (8) via an annular gap (19), and formed of a transparent material, for holding a collimator lens (2), and a semi-conductor laser light source (1) fitted under pressure in the fixation holder (8). An ultraviolet curing adhesive (18) is uniformly filled in the gap (19). Before the ultraviolet curing adhesive (18) is cured, the lens-barrel (10) is movable in an optical axis direction (Z) and in two-dimensional directions (directions of arrows X and Y) on a plane perpendicular to the optical axis direction (Z) with respect to the fixation holder (8).

Abstract: Known power lasers have outstanding electrical, optical and mechanical properties, in spite of different temperature conditions during switching on and during operation. However, they are expensive. These properties are retained, despite cheaper production costs in that, starting from a solid monolithic optical bench, several mirror blocks and intermediate blocks are mechanically rigidly connected to this, and are shaped such that they do not deflect during chip-removing machining, and those bores necessary for the laser path are only then provided.

Abstract: A laser beam generator for making wavelength conversion automatically controls the length of an external resonator of a laser source to perform wavelength conversion at a high efficiency by pulling-in a servo using a resonator length error signal and a reflected light signal. A sample-and-hold circuit is used to detect the error signal from the detected light signal which is reflected from the external resonator.

Abstract: An optical device (7) for use in optical write, read, inspection or measuring apparatuses comprising a diode laser (8) for generating a radiation beam (11) and an optical system (9) for concentrating and guiding the radiation beam. The diode laser is a pulsed laser and a feedback element is arranged in the radiation path at a specific distance (d) from the diode laser. By giving the element a suitable reflection coefficient, a stabilized radiation beam is obtained. The beam direction can be varied by rendering the wavelength adjustable and by making use of a dispersive element.

Abstract: A control system for a laser includes a resonator cavity having a displaceable control mirror, a drive for displacing the control mirror, sensor devices located to sense the position of the outputted laser beam, and a control circuit connected to the sensor devices for measuring the positional deviation of the outputted laser beam from a reference position and for controlling the drive in response thereto to angularly displace the control mirror to correct the positional deviation.

Abstract: A pulsed laser utilizing an oscillating or rotating intra cavity photon deflector means to extract a beam transverse to the long axis of the resonator from intracavity power. The moving photon deflector is supported and set into motion either mechanically or electromagnetically within the resonator and in the path of lasing photons, thereby intercepting and deflecting photons out of the resonator.Movement of the deflector within the path of lasing photons results in the circumferential deflection of photons with the most intense concentration being deflected from that portion of the surface of the deflector which first intercepts the circulating intracavity photon stream. As lasing photons are deflected from the leading edge of the deflector, lasing action is instantaneously reestablished after the trailing edge moves through the photon stream. Wherever the deflector does not intersect the normal trajectory of photons in the laser cavity, lasing action is automatically reestablished.

Abstract: Laser resonator, particularly for carbon dioxide lasers, with two resonator nd mirrors having active material between two fully reflecting end mirror faces, which form an unstable resonator cavity, and with at least one third, completely reflecting mirror face reflecting the laser radiation prior to its coupling out through a coupling-out opening of the resonator. So that the laser only requires a reduced degree of coupling out and/or has an improved beam quality, it is constructed in such a way that, in addition to the unstable resonator cavity, between the two end mirrors is provided at least one stable resonator cavity and that the stable resonator cavity is made from the same active material of the third mirror face as the face of one of the two end mirrors with the face of the other end mirror.

Abstract: Methods and apparatus for providing substantially complete correction of thermally-induced aberrations of the gain medium in an end-pumped laser system with at least one aspheric surface that is positioned within the optical cavity of the laser system. The at least one aspheric surface is shaped to substantially cancel all of the thermally-induced aberration of the gain medium at the normal power level of the laser system.

Abstract: An optical fiber feedthrough is characterized by an isolator disposed completely within the feedthrough tube.

Abstract: Passive waveguides within a monolithic semiconductor structure are coupled to angled facets to reduce the reflectivity of the angled facets and thereby increase the gain available from for the amplification waveguides coupled to the passive waveguides.

Abstract: A diode laser and optical system uses the minimum number of elements to obtain a small diameter beam (1 mm). A large numerical aperture lens collimates the full energy from the diode and the oval shaped output of the collimator is corrected for astigmatism by means of a cylinder lens and made circular by two identical prisms arranged to receive the corrected, collimated beam directly at a right angle surface of the first prism and transmit the beam after deflection to the second prism further which demagnifies the beam producing the round (.ltoreq.1 mm diameter) beam spot output of the laser. The output beam is well collimated (1 mRad) and wave front aberration is diffraction limited. The spot size at 50 feet distance is maintained. In order to hold total Gaussian distribution energy, the prisms are coated with a multilayer dielectric thin film eliminate reflection and to transmit the TE mode wave without loss at the Brewster angle.

Abstract: A compact semiconductor laser light source providing short wavelength (ultraviolet, blue or green) coherent light by means of frequency doubling of red or infrared light from a high power diode heterostructure. The high power diode heterostructure is a MOPA device having a single mode laser oscillator followed by a multimode, preferably flared, optical power amplifier. A tunable configuration having an external rear reflector grating could also be used. A lens could be integrated with the MOPA to laterally collimate the light before it is emitted. Straight or curved, surface emitting gratings could also be incorporated. An astigmatism-correcting lens system having at least one cylindrical lens surface is disposed in the path of the output from the MOPA to provide a beam with substantially equal lateral and transverse beam width dimensions and beam divergence angles. A nonlinear optical crystal or waveguide is placed in the path of the astigmatism-free symmetrized beam to double the frequency of the light.