Abstract: A high-output, single fundamental transverse mode solid state laser is disclosed which uses a semiconductor laser array as an excitation light source. The solid state laser comprises: a laser element which includes a core containing an element added as a laser medium, a cladding containing no such laser medium element, and reflecting mirrors coated over the cladding surface for repeatedly reflecting incident excitation light so that it may repeatedly pass through the core; an excitation light source formed by semi-conductor laser or light emitting diode array; means for guiding the excitation light from the excitation light source to one side of the laser element for incidence thereto; and a resonator for the oscillation of the solid state laser.

Abstract: A dual-wavelength laser system with intracavity, sum-frequency mixing including a bifurcated resonant cavity having a first arm, a second arm and a common arm; a first laser element located in the first arm for providing a first input laser beam of a first wavelength; a second laser element located in the second arm for providing a second input laser beam of a second wavelength; a nonlinear-mixing element in the common arm; and a beam combining device for combining the first and second beams and submitting them to the nonlinear-mixing element for providing an output laser beam of a third wavelength whose energy is the sum of the energy of the input laser beams.

Abstract: An installation for the formation of a laser beam suitable for isotope separation. According to the present invention, a pumping means of tunable chains are constituted by a plurality of solid matrix lasers, e.g., of the frequency-doubled, switched YAG type, having optical fibers guiding the pumping light to the tunable chain. Such a system finds particular application to isotope separation.

Abstract: In a laser diode pumped solid state laser, a primary solid state laser medium containing a rare earth metal is pumped by a semiconductor laser, and the wavelength of a laser beam having been obtained from the solid state laser oscillation is converted by a nonlinear optical material into a different wavelength. A solid state laser medium for injection locking is located between the primary solid state laser medium and the semiconductor laser. The solid state laser medium for injection locking is pumped by the semiconductor laser and produces a laser beam for injection locking through solid state laser oscillation in a single longitudinal mode, such that the laser beam for injection locking may impinge upon the primary solid state laser medium.

Abstract: A laser-diode-pumped solid-state laser includes a solid-state laser rod which is doped with a rare-earth material such as neodium and has a wavelength converting function and a semiconductor laser which pumps the solid-state laser rod. Opposite end faces of the solid-state laser rod are formed into resonator mirrors, and a wavelength-converted wave such as a second harmonic of the laser beam oscillated by the solid-state laser rod or a sum frequency wave of a laser beam oscillated by the solid-state laser rod and a semiconductor laser beam emitted by a semiconductor laser is extracted.

Abstract: A solid laser comprises an anisotropic laser crystal, to which a rare earth element has been added, a pumping device, which causes a pumping beam to impinge upon the laser crystal, and a resonator mirror, which oscillates a solid laser beam having been produced by the laser crystal. The laser crystal is located in an orientation such that its crystallographic axis may makes an angle with respect to a laser oscillation axis. A device linearly moves the pumping means with respect to the laser crystal and the resonator mirror such that only either one of ordinary rays and extraordinary rays, which are produced by the laser crystal, may oscillate selectively, or a device linearly moves the resonator mirror with respect to the laser crystal and the pumping means such that only either one of ordinary rays and extraordinary rays, which are produced by the laser crystal, may oscillate selectively. A single desired beam radiation line is thus selected easily.

Abstract: The optical mirror incorporates a lightguide (20) produced on a surface (23) of a substrate (22) and used for the propagation of a light beam (36) in a direction parallel to said surface, a cavity (30) made in the lightguide (20) and having in the propagation direction a first (32) and a second (34) walls oriented perpendicular to said direction and having in section approximately the shape of a circular arc, the distance (L) separating the two walls being equal to the radius of curvature (R) of the second wall at the optical axis (37) of the mirror and a reflecting material layer (38) deposited solely on the second wall in order to reflect the light beam towards the first wall, the second wall forming a concave reflecting surface.

Abstract: A pulse format for a laser system is disclosed for maximizing the energy delivered to a target immersed in an absorbing liquid. A first pulse is generated having an energy sufficient to initiate the formation of a vapor bubble in the liquid medium adjacent the end of the delivery device. A second, high energy pulse is generated after the vapor bubble initiated by the first pulse has expanded an amount sufficient to displace the liquid between the delivery device and the target. In this manner, the second pulse is delivered directly to the target and little energy is lost to the liquid medium.

Abstract: A high power electromagnetic pulse driver for generating sub-microsecond rise time pulses having energy contents greater than 1 joule includes an electromagnetic pulse compressor and an electromagnetic shock line for compressing the leading edges of those pulses. The shock line may use non-linear materials whose permeability or permittivity vary greatly with varying field strength. One material whose permeability varies by a useful amount is metglass, an amorphous alloy of silicon and iron. The high power electromagnetic pulse driver may drive gas discharge lasers.

Abstract: A method and apparatus for pumping a coolant through a laser cavity to cool the laser. The apparatus has a titanium housing and a casing containing a rotatable titanium hollow shaft. A titanium impeller is located at one end of the shaft within the housing and rotates with the shaft to pump the fluid through a laser. Disposed within casing and attached to the shaft are a plurality of permanent magnets. External to the casing are stator windings through which current flows to create a magnetic field that rotates the permanent magnets, shaft and impeller. When the impeller is rotated, the coolant is passed through the housing and to the laser. The impeller also forces the fluid passing through the shaft and into the casing to cool and lubricate the pump. The magnets are encased in a titanium sleeve attached to the titanium shaft to prevent the coolant from contacting with the magnets.

Abstract: A tunable optical waveguide laser arrangement includes a solid optical waveguide capable of guiding light along an axis between axially spaced ends thereof and being at least in part of an excitable material that emits light in response to stimulation by light. Stimulating light is launched into the waveguide for axial propagation therein and attendant emission of light by the excitable material. Two end reflectors are situated in the waveguide, each at one of the axially spaced ends thereof and extending normal to the axis to delimit a laser cavity. Each of the reflectors is constituted by a Bragg grating consisting of a multitude of axially consecutive grating elements constituted by periodic refractive index perturbations with a given periodicity. The length of the cavity, the peak reflectivity of the Bragg gratings and the gain of the excitable material are so coordinated with one another as to enable lasing in only a single longitudinal mode.

Abstract: An eye-safe short pulse room-temperature solid state laser emitting at about 2.1 microns is optically pumped by diode lasers emitting at about 1.9 microns Absorption spectra of Ho ions in YAG (Yttrium Aluminum Garnet) and YLF (Yttrium Lithium Fluoride) host crystals are described. Optical pumping is performed by high-power diode lasers emitting at about 1.91 microns consisting of a GaInAsSb/AlGaAsSb quantum-well active region and AlGaAsSb cladding layers grown on GaSb substrates.

Abstract: A laser diode pumped solid laser comprises a solid laser medium, to which a rare earth metal has been added, a semiconductor laser, which produces a laser beam for pumping the solid laser medium, and a condensing lens, which causes the laser beam to converge in the solid laser medium. The condensing lens is located such that an optical axis of the condensing lens may deviate in the width direction of a semiconductor laser active layer from a center of irradiation area of the semiconductor laser. The amount of light returning to the semiconductor laser is thereby reduced markedly, and good stability in the output power of the laser diode pumped solid laser is obtained. A nonlinear optical material for converting the wavelength of a laser beam, which has been produced by the solid laser medium, into a different wavelength may be located in a solid laser resonator.

Abstract: A novel diode bar, side-pumped laser cavity design having high optical to optical conversion efficiency and a high slope efficiency is provided. A slab geometry with a single, high angle of incidence internal reflection permits gain to be accessed near the pump face of a laser material which absorbs strongly at the pump wavelength.

Abstract: A three-stage magnetic modulator utilizing magnetic pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.

Abstract: A pulsed transversely excited gas laser device includes a pair of main electrodes having main surfaces opposing each other across a main discharge gap and extending along the optical axis of the laser. A corona discharge preionizer for radiating ultraviolet radiation is substantially accommodated within a recess formed on the main surface of one of the main electrodes at an upstream side of the foot of the main discharge 3. The corona discharge preionizer is separated from the inner wall and bottom surface of the recess except at a surface portion thereof which is in contact with a projection extending sideways from a side wall of the recess next to the main discharge. The corona discharge generated over the preionizer radiates ultraviolet radiation to preionize the laser gas.

Abstract: A wavelength stabilization apparatus and method for a superfluorescent source comprising a SFS (superfluorescent source) comprising a fiber with a core doped with lazing material. The SFS source produces SFS light with an SFS wavelength when pumped with pump light from a pump light source having a pump light wavelength. An output controller responds to a sample of the SFS light and operates to maximize the power of the sample of SFS light by automatically adjusting the pump light wavelength. The output controller also has a pump power controller responsive to a sample of the pump light from the pump light source for stabilizing the output power of the sample of the pump light with respect to a predetermined reference output power level.

Abstract: The invention relates to a pumping lamp for use with lasers comprising a porous substrate loaded with a component capable of emitting light upon interaction of the component with exciting radiation and a source of exciting radiation. Preferably, the pumping lamp comprises a source of exciting radiation, such as an electron beam, and an aerogel or xerogel substrate loaded with a component capable of interacting with the exciting radiation, e.g., a phosphor, to produce light, e.g., visible light, of a suitable band width and of a sufficient intensity to generate a laser beam from a laser material.

Abstract: A diode laser array made from a plurality of linear laser diode array assemblies affixed and in good thermal communication with bodies containing micro-heatpipes. Assemblies are stacked in a vertical manner to form two dimensional arrays. Each assembly is connected electrically and mechanically to adjacent assemblies to form the final assembly. In one embodiment the bodies are arranged in a vertical stairstep manner such that radiation from an upper assembly stimulates emission in adjacent lower assemblies thereby achieving frequency locking. In another embodiment said micro-heatpipe containing second bodies are fabricated from materials with a coefficient of thermal expansion closely matching with a coefficient of thermal expansion closely matching that of the laser diode array subassemblies. In another embodiment the assemblies form the evaporator of a second heatpipe device cooling means.

Abstract: A phase conjugation mirror (20) for use in a phase conjugation resonator (1). The phase conjugation mirror provides a nonlinear resonance enhancement for a coherent optical signal incident thereon. The phase conjugation mirror is comprised of a semiconductor material having a characteristic bandgap energy selected to be at an absorption bandgap edge, or slightly greater than the absorption bandgap edge, for the coherent optical signal.

Abstract: The architecture of the present invention has been driven by the need to solve the beam quality problems inherent in Brewster's angle tipped slab lasers. The entrance and exit faces of a solid state slab laser are cut perpendicular with respect to the pump face, thus intrinsically eliminating distortion caused by the unpumped Brewster's angled faces. For a given zigzag angle, the residual distortions inherent in the remaining unpumped or lightly pumped ends may be reduced further by tailoring the pump intensity at these ends.

Abstract: A switch device used for a laser device, includes series-parallel connected switch elements or modules. The switch elements or modules are simultaneously turned on by trigger signals from trigger circuits. The transmission lines for connecting the trigger circuits to respective switch elements are equal to one another in length. A protecting circuit is provided for the switch elements, and indicators are provided for indicating the shortcircuit of the switch elements. In the switch device, the number of wires for the switch elements is made small and heat generated from the switch elements is effectively radiated. The modules are easily stacked, and firmly connected to a control unit for controlling the switch elements. A discharge excited laser device using the switch device has a high efficiency and a long lifetime and is reliable.

Abstract: A laser light generating apparatus comprises a light source for generating an exciting light beam, a condenser lens for converging the exciting light beam from the light source, a laser medium for generating a laser light of first wavelength by the radiation of the exciting light beam supplied thereto through the condenser lens, a nonlinear optical crystal element for generating a second laser light by the radiation of the first laser light generated from the laser medium, a pair of reflecting means for constituting a laser resonator together with at least the laser medium and the nonlinear optical crystal element, a deflecting element for deflecting an optical axis of the second laser light emitted from reflecting means provided at the emitting side of the pair of reflecting means, detecting means for detecting a part of a light beam output from reflecting means disposed at the output side of the pair of reflecting means, control means for controlling the light source on the basis of a detected output from t

Abstract: A method and apparatus (242) generates intense spectral emissions (68) by associating a porous-Si layer (230) with a rare earth-doped CaF.sub.2 film (234) so that the rare earth-doped CaF.sub.2 film absorbs optical emissions (222) from the porous-Si layer (230). Circuitry (228, 244, and 238) associated with the apparatus (242 and 226) activate the porous-Si layer (230) to produce the optical emissions (222). The porous-Si layer (230) may be formed electrically, by chemical vapor deposition, or by anodizing crystalline silicon.

Abstract: An upconversion laser system that uses solid state components throughout and achieves such operation with a continuous or quasi-continuous single band infrared pumping source using successive energy transfers between the sensitizer and activator in the host of the lasant upconversion material.

Abstract: Prior art fiber-optic amplifiers which are used in a fiber-optic link to amplify the light signals to be transmitted have the disadvantage that the semiconductor lasers employed as pump lasers are highly sensitive to feedback, so that the stability of the light-signal transmission is impaired by pump light reflected back into the pump lasers.According to the invention, the operating current for such pump lasers (4) contains a noise current, so that the pump laser emits its pump light in many modes, which makes it insensitive to feedback.To prevent the noise component of the pump light which is caused by the noise current from affecting the amplification of the light signals to be transmitted, the noise current is filtered in such a way that its spectral components have frequencies which lie above the reciprocal lifetime of that energy level of the active laser medium which causes the amplification of the light signals.

Abstract: The object of the invention is a free electron laser with two self-stimulating ondulators at higher order harmonics comprising, in combination, a first section comprising an ondulator (UM1) operating as an oscillator, to generate coherent radiation with a determinate wave length (.lambda.) and simultaneously the higher harmonics relevant thereto, and a second section comprising an ondulator (UM2) operating as an amplifier, tuneable at the frequency and the relevant harmonics of the coherent radiation generated in the first modulator (UM1).

Abstract: A gas laser device, including an a.c. power source for generating a.c. output voltage and a pair of electrodes positioned sandwiching discharge gap through which laser gas circulates. The pair of electrodes are connected to the a.c. power source for applying the a.c. voltage across the electrodes to achieve discharge in the discharge gap such as to create a positive column region and boundary layer regions, thereby to generate laser light. The positive column region is created in the discharge gap and a.c. power injected therein contributes to laser excitation. The boundary layer regions is created in a vicinity of one of the pair of electrodes, respectively and a.c. power injected therein does not contribute to laser excitation. A frequency of the a.c. power source is set to at least 700 kHz and an a.c. output voltage of the a.c. power source is set at a level such that a voltage in the positive column region is larger than a burden voltage in the boundary layer regions.

Abstract: To produce blue light by means of a laser, pumped light is coupled into a birefringent, nonlinear crystal (5) in a variable frequency laser (1) from a laser diode pumped light source (7, 8, 9) via an input mirror (3). Due to adjustment of the inclination of the crystal (5) or with the aid of tempering means (6) for the crystal, most of the pumped light is absorbed in the crystal (5)--upon suitable polarization of the pumped light--while the rest is available for a frequency mixture of the fundamental Wave of the laser and of the pumped light. Via an output mirror (4) blue laser light with a Wavelength of e.g. 459 nm is coupled out, with a fundamental wave of e.g. 1064 nm and pumped light with a wavelength of e.g. 806 nm.

Abstract: A Bragg reflector for selecting a specific spectral line from an output of a free electron laser (FEL) driven in the Raman regime to feed back the spectral line to the FEL. The Bragg reflector comprises at least one reflector pipe (4A), and a plurality of ring-formed plates (8) with their outer peripheries fitted to the inner periphery of the reflector pipe. The plurality of the ring-formed plates are spaced apart from each other at a constant spacing prescribed so that the alignment of the ring-formed plates provide the Bragg reflection of microwaves or far-infrared waves of a prescribed wavelength.

Abstract: An electric power supply for a laser includes a heating module (44) connected to the electrodes (16,18) of an enclosure (12) containing an active material, and supplies an electric pulse for the vaporization of the active material. An excitation module (14) supplies an electric pulse for exciting the active material. As the operation of the laser is repetitive, the excitation pulse preionizes the active material with a view to triggering the heating pulse.

Abstract: A radiation wavelength conversion device is implemented in the form of a waveguide that includes a single crystal halide-based cladding layer, and a halide-based active layer. The active layer has a greater refractive index than the cladding layer, is approximately lattice matched with the cladding layer, and includes a dopant that causes it to respond to input radiation at one wavelength by emitting radiation at a different wavelength. The active layer can either form part of a laser resonator cavity, or can operate through spontaneous emission. It is preferably about 3.5-5 microns thick to induce single-mode propagation, and can be divided into separate waveguiding channels to limit beam fanning. The device is operable at room temperature, and can be fabricated using conventional microelectronics techniques.

Abstract: Four-fold and higher order lasers pumped by multiphoton absorption, avalanche mechanisms, or other means of internal upconversion for continuous-wave and continuous-wave mode-locked lasers. A solid-state laser system is contained within an astigmatically compensated cavity containing first and second mirrors. The gain medium is formed of a crystal of lithium yttrium fluoride heavily doped (5%) with trivalent erbium, or another form of crystal, such as CaF.sub.2 where the dopant atoms are clustered in quartets. The crystal, in a lithium yttrium fluoride embodiment, is approximately 3 mm thick with both sides thereof being polished flat to a laser grade finish. A pumping source supplies a pumping energy having a wavelength of 1.5 .mu.m to the gain medium, which wavelength is considerable longer than the output wavelength (701.5 nm) of the laser system. The gain medium may additionally be an alkali vapor formed of Cesium or Rubidium.

Abstract: The present invention relates to a solid state laser generation apparatus which is composed of modularized solid state lasing units which enable construction of a compact cascading laser apparatus having a low lasing threshold value and a high laser generation efficiency. A lasing rod and the electrodes for the excitation of the rod are housed in a common module casing which has depressed sections on its external surface. When assembling two modular units, one of the module units is rotated axially with respect to the other in such a way to insert the electrodes into the depressed section on the external surface of the neighboring module so as to minimize the mechanical interference caused by the neighboring components. By utilizing such a modular arrangement, the lasing rod spacing between the neighboring module units can be shortened, thus resulting in lower coupling losses between the adjacent rods even during the initial phase of the operation.

Abstract: Solid state laser gain media of the composition Cr.sup.+3 :XYZF.sub.6 wherein X is an alkali metal ion; Y is an alkaline earth metal ion, Cd.sup.+2 or Mg.sup.+2 ; and Z is Al.sup.+3, Ga.sup.+3 or Sc.sup.+3 are provided with gradient Cr doping levels for reducing thermally generated stress/strain in the lasing operation.

Abstract: A method of producing a small expansion of laser light, in a pulse laser apparatus, including producing a small preliminary laser light by pumping a laser medium, and then, after an appropriate time lag, then pumping the preliminary laser medium at a higher intensity than the first pumping, thereby producing a laser light which is smaller in beam expansion than in the case where a preliminary pumping is not performed. The laser light which is smaller in beam expansion is due to the population inversion occurring in a small beam expansion part of pulse laser light obtained by the preliminary pumping.

Abstract: A flashlamp-excited laser for producing a pulsed beam of laser light of long duration (e.g., greater than 500 microseconds) comprises a flashlamp driven by a pulse forming circuit which generates a ramp pulse having an amplitude generally increasing with time during substantially the entire duration of the pulsed beam of laser light produced by the laser.

Abstract: Efficient, low threshold laser emission from a laser crystal doped with chromium and neodymium ions is obtained when pumped by visible laser diodes in the range of 610 nm to 680 nm. A typical laser Cr,Nd:GSGG crystal having an extraordinarily broad absorption bandwidth allows high pump efficiencies when using visible laser diodes, particularly in comparison to the Nd:YAG laser. The broad absorption bandwidth tolerance of the Cr,Nd:GSGG crystal to the pumping wavelengths allows visible diode pumping of the neodymium transition without regard to the wavelength of the visible diodes. Longitudinal or end-pumping to take advantage of the emission properties of the visible laser diodes, a nearly hemispherical laser resonator configuration and other co-doped Cr,Nd laser host materials are disclosed. Consequently, costs are reduced for the semiconductor pump as well as producing a compact, efficient, lightweight and reliable laser previously unachievable with other types of laser or lamp pumping.

Abstract: An optical device includes a semiconductor laser monolithically integrated on a substrate having a branched cavity extending above a plane that is coplanar with a base surface of the substrate, and an adjustable optical power light source for radiating light into the cavity of the semiconductor laser thereby controlling the operation of the semiconductor laser optically.

Abstract: Bulk gallium arsenide having a high hold-off voltage is optically activated by a laser resulting in high power output. A high voltage input is applied to a semi-insulating gallium arsenide material. The gallium arsenide material is activated by laser light, thereby resulting in large current conduction. An external oscillating signal is superimposed on the high current resulting in a high power output.

Abstract: This invention relates to face-pumped slab lasers of the type that have laser head assemblies constructed of individual components, which are rigidly attached together, in order to form an integral structure. Such structures of this type, generally, allow a face-pumped slab laser component to be assembled and disassembled easily and quickly.

Abstract: Devices and methods are taught by this invention of populating excited energy levels with fundamental particles. When these populated excited energy levels are further pumped, a population inversion used in quantum electronic applications can result. Each of the various methods involve pumping on an excited energy level of an elemental physical system to cause, by the absorption of energy, the transition of fundamental particles from the excited energy level to a higher energy level. Part of the energy is used for transition of fundamental particles residing in neighboring elemental physical systems from the lowest energy to the excited energy level.

Abstract: A pulsed laser system capable of operating at higher repetition rates, while maintaining the efficiency and beam quality of the output pulses comprises first and second gain media with one or more pump energy transducers, such as flashlamps, coupled with each of the gain media. A power supply generates a first sequence of pulses of input power and a second sequence of pulses of input power which drive respective subsets of the pump energy transducers in an independent timing relationship. Thus, two non-aligned 50 Hz sequences of input pulses which are interleaved generate an output pulse stream at 100 Hz from the laser system with the efficiency, beam quality, and average power comparable to that of a 50 Hz laser. By pumping subsets of the pump energy transducers coupled to a laser system in an interleaved fashion, higher repetition rates may be achieved with better output beam quality and higher average power than has been obtainable with prior art systems.

Abstract: A laser source which operated under the principals of cooperative unconversion produces controllable optical pulses at wavelengths which are shorter than the wavelength of the laser energy which pumps the gain medium. The source is a solid-state laser which employs a five percent Er:LiYF.sub.4 crystal which is arranged in an astigmatically-compensated 3-mirror cavity. Pumping is achieved at 1.5 microns in the infrared, and the system operates in a continuous-wave, mode-locked fashion in the green spectral region at approximately 544 nm. The cooperative inversion mechanism involves energy pooling by trios of excited rare earth dopant ions in the laser medium. Q-switching is achieved with the use of intracavity amplitude modulation so as to achieve three-fold upconversion. A 3-mirror astigmatically-compensated cavity with the gain medium permits modulation of losses in a manner which cannot be achieved with known systems and achieves high stability.

Abstract: In a discharge excitation gas laser device such as an excimer laser device provided with laser medium gas and a pair of electrodes opposite to each other in a gas-tight vessel, the laser medium gas is discharge-excited while inverting the polarity of a DC pulse voltage applied to the pair of electrodes opposite to each other for every pulse. In this way distribution of atoms and ions constituting the laser medium gas in the discharge region including the neighborhood of the main electrodes is made uniform even at a high repetition rate oscillation. Thus it is possible to realize a discharge excitation gas laser device having a good stability of DC pulse discharge without increasing unnecessarily the flow speed of the laser medium gas and no lowering in the pulse energy owing to a high efficiency operation.

Abstract: The invention is directed to a frequency-doubling solid state laser having pump light sources at opposite ends thereof. A folding and out-coupling mirror is antireflection coated on both sides with respect to the wavelength of the light generated by the pump light sources. The pump light sources include a total of four laser diodes with each laser diode generating 3 Watts of light power. An output power at 532 nm is obtained using a Nd:YAG laser rod and a frequency-doubling crystal made of potassium titanyl phosphate. The folding angle defined by the folding and out-coupling mirror is in the range of 10.degree. to 60.degree. and is typically 50.degree..

Abstract: A color center laser is provided with a crystal disposed within a longitudinally pumped cavity. Optics are provided to transversely excite the crystal. Both a circular lens and a cylindrical lens focus an auxiliary beam into the crystal of the color center laser to produce (F.sub.2.sup.+).sub.A color centers for lasing. The cylindrical lens is used to focus the auxiliary beam to a narrow focal line. The circular lens is used to adjust the length of the focal line. By adjusting the length of the focal line, an entirety of the pump beam is used for excitation. The lenses thus collimate and focus the focal line to a length within an active volume in the crystal of the color center laser essentially equal to a length of the crystal.

Abstract: In a solid-state laser device which pumps a solid-state laser medium in a laser resonator by an excitation laser beam generated from a semiconductor laser unit and which emits an output laser beam, a photo detector detects intensity of the output laser beam to produce a photo detection signal which corresponds to the intensity of the output laser beam and which is sent to a controller. The controller controls the semiconductor laser unit in response to the photo detection signal and adjusts intensity of the excitation laser beam to keep the intensity of the output laser beam substantially constant. The solid-state laser medium may be pumped from an end surface or a side surface. An optical function element, such as a wavelength conversion element, a Q switch element, may be located outside or inside of the laser resonator.

Abstract: A laser system and processing method exploits the absorption contrast between the materials from which a link (12) and an underlying substrate (22) are made to effectively remove the link from the substrate. Laser output in a wavelength range of 1.2 to 2.0 .mu.m (30) optimizes the absorption contrast between many high conductivity materials (e.g., metals) and silicon substrates and permits the use of laser output in a wider range of energy or power levels, pulse widths, without risking damage to the silicon substrates or adjacent circuit structures. Existing link processing laser systems can be readily modified to operate in the 1.2 to 3.0 .mu.m range.

Abstract: An optically pumped single mode laser, e.g. Nd:YAG crystal (20) with planoconcave mirrors is increased in efficiency by an order of magnitude to about 8% by optics (25, 27) for focusing the high power multimode output of laser diode arrays (21, 22) into the mode volume (20') of the laser medium (20). A plurality of these optically pumped single mode lasers (1-4) may be cascaded in a ring with dichroci mirrors (M.sub.1 -M.sub.4) at the corners for coupling in the laser diode arrays, each having its own means for spatially tailoring its beam to concentrate pump distribution inside the lasing mode volume of the medium. An InGaAlAs pump diode (30) with its wavelength of the same as a lasing medium makes the ring unidirectional.The questions raised in reexamination request No. 90/002,473, filed Oct. 10, 1991, have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1,570(e).