Abstract: A laser apparatus includes a laser resonator having a first reflective surface and a second reflective surface, the laser resonator further including a laser medium disposed between the first reflective surface and the second reflective surface for processing light reflected from the first and second reflective surfaces to output a laser beam to be resonated, and a resonator loss varying unit disposed between the first reflective surface and the second reflective surface of the laser resonator, the resonator loss varying unit being capable of switching a state thereof between a first state having a resonance frequency substantially coinciding with one of frequencies at which laser oscillation of the laser resonator is possible and a second state having the resonance frequency shifted to the value that is substantially different from any one of the frequencies at which laser oscillation of the laser resonator is possible to vary a loss of the laser resonator.

Abstract: A laser comprises an active element and two resonators wherein each resonator further comprises a highly reflective resonator element and an output coupling element which reflects the radiation of the active element in itself. The active element amplifies incident radiation from a solid angle range by a normal of the active element which is distinctly greater than zero. The resonators are arranged relative to the active element such that each resonator reflects the radiation on the active element at a different angle of incidence within the solid angle range.

Abstract: A multifrequency laser (MFL) eliminates nonlinearities produced in the "shared" waveguide of the MFL laser (the section in which all the lightwaves from all the lasers pass) by either making the shared waveguide as short as possible to mimimize the production of mixing product signals or using a channel spacing that is unequal such that any mixing product signals formed from the multifrequency optical laser signal do not overlap in frequency with any of the signals of the multifrequency optical laser signal.

Abstract: A solid-state laser oscillating device which is inexpensive and capable of obtaining a high power. A plurality of laser crystals (YAG laser crystals, etc.) (1a, 1b, 1c) are arranged along the optical axis of an optical resonator so as to maintain optical contact with one another. Adjacent ones of the laser crystals have surfaces facing each other with an adhesive layer (10, 20) interposed therebetween, to form an array in a straight-line as a whole. An adhesive having a low light absorbance with respect to a laser beam of oscillation wavelength or an excitation light is used for forming the adhesive layers (10, 20). If the refractive index of the adhesive is substantially equal to that of the laser crystals, optical matching is achieved. The adhesive layers (10, 20) may be replaced by some other transparent material. The adjacent laser crystals may be arranged with a narrow gap therebetween or held in surface contact with each other.

Abstract: In an optical device having a diffraction grating and at least two surfaces for reflecting light, the oscillation state is switched between a first oscillation state mainly based on resonance by distributed reflection by the diffraction grating, and a second oscillation state mainly based on Fabry-Perot resonance between the two surfaces. The characteristics of one of two modes to be used are improved at the cost of coherence of the other mode.

Abstract: A laser source has two or more laser units and coupling means for coupling the laser beams from each unit so as to deliver a resulting beam for treating a surface. Concurrently with the laser surface treatment, the characteristics of the laser beam from each unit are adjusted to produce a resulting laser beam with a time profile of energy optimally adapted to said laser surface treatment. Homogenizing means homogenize the energy distribution of the resulting laser beam, so that the energy and spatial distribution of said resulting laser beam are concurrently adapted for the selected surface treatment.

Abstract: An optical, semiconductor micro-resonator device includes a microcavity resonator and a pair of adjacent waveguides. The microcavity resonator may be formed as a disk, a ring or closed loop with arbitrarily curved circumference with a diameter of approximately 56000.lambda..sub.lg /n.sub.res or less where .lambda..sub.lg is the longest operating wavelength of light and n.sub.res is the propagating refractive index. A portion of each of the waveguides is disposed adjacent to the microcavity resonator wherein the adjacent portion may be either tangential to the microcavity resonator or curve about a respective portion of the microcavity resonator. Light propagating in the first waveguide with a wavelength on resonance with the microcavity resonator is coupled thereto via resonant waveguide coupling and from the microcavity resonator the light is coupled to the second waveguide for output therefrom.

Abstract: A pulsed optical parametric oscillator comprising a spectrally pure source or emitting pumping wave pulses, a non-linear crystal to which the pumping wave is applied, a resonant cavity for the complementary wave defined by two same-axis mirrors situated on opposite sides of the crystal, a cavity for the signal wave defined by two same-axis mirrors situated on opposite sides of the crystal, and means for adjusting the length of one or both cavities, wherein the oscillator is a monomode pulsed parametric oscillator and wherein one of the two mirrors for each cavity is situated between the two mirrors of the other cavity.

Abstract: An interferometric semiconductor laser (YL) as well as optoelectronic arrangements with such a laser are disclosed. The laser has a special coupling segment (Z) which allows high optical output to be obtained without affecting the filtering function or significantly restricting the tuning range of the laser. Such a laser can be coupled with low loss to a subsequent optoelectronic component (e.g., a wavelength converter (WK)) which is monolithically integrated with the laser.

Abstract: An intracavity, frequency-doubled, external-cavity, optically-pumped semiconductor laser in accordance with the present invention includes a monolithic surface-emitting semiconductor layer structure including a Bragg mirror portion and a gain portion. An external mirror and the Bragg-mirror portion define a laser resonant-cavity including the gain-portion of the semiconductor layer structure. A birefringent filter is located in the resonant-cavity for selecting a frequency of the laser-radiation within a gain bandwidth characteristic of semiconductor structure. An optically-nonlinear crystal is located in the resonant-cavity between the birefringent filter and the external mirror and arranged to double the selected frequency of laser-radiation.

Abstract: A high energy chemical laser capable of being operated in an aircraft to interdict and destroy theater ballistic missiles is provided. A key to the chemical laser of the invention is the use of individual chemical lasers whose individual photon energy outputs can be combined into a single high-energy laser beam.

Abstract: A laser light source apparatus and a control method for automatically sitting the temperature of a KTP crystal to an optimal temperature, and to follow up in variations of the optimal temperature. A predetermined temperature step is periodically added to a temperature corresponding to a reference potential, the addition of the temperature step is stopped when a temperature at which the UV laser output is substantially maximized, and a temperature step smaller than the temperature step .DELTA.T is successively subtracted from the temperature Tc, thereby automatically setting the KTP crystal temperature to the optimal temperature. Also, the difference between the two values of the UV laser output before and after each step addition of the temperature step is calculated and step subtraction is started when the difference becomes reversed in polarity, thus controlling the KTP crystal temperature so that the UV laser output is always maintained at the maximum.

Abstract: Laser apparatus for delivering optical power to an output port comprises first and second fiber lasers having at least partially overlapping cavity resonators. In one state the lasers are phase locked; in another they are not. An intracavity polarization transformer (e.g., a polarization modulator or a segment of PMF) determines the phase state of the apparatus. In each state the reflectivity of a reflector common to the lasers determines the amount of optical power which is delivered to the output port. In one embodiment the apparatus has a plurality of output ports to which separate utilization devices are coupled. The phase state of the lasers and the reflectivity of the common reflector determines how the optical power is allocated among the devices.

Abstract: In order to improve upon a laser system, comprising a laser-active medium which is arranged between mutually opposed waveguide surfaces of an optical waveguide and a resonator which by means of resonator mirrors defines a coherent resonator radiation field permeating the optical waveguide and from which a plurality of mutually coherent radiation fields issue, in such manner that higher laser output power levels can be attained it is proposed that the plurality of radiation fields are conducted as coupled-out radiation fields to a coupling element, and that the coupling element combines the plurality of radiation fields with a defined mutual phase relationship to form one single coherent output radiation field.

Abstract: An optical fiber amplifier is pumped by a pair of pump lasers which have at least partially overlapping resonators. In one embodiment, the fiber gain section of the amplifier is located external to the resonators. In another embodiment, the coupler, which couples the pump lasers to the gain section, is located at least partially within said resonators. In a preferred embodiment the resonators are provided with polarization selection properties, and the outputs of the pump lasers are coherent.

Abstract: A laser cavity assembly includes means (12, 13, 14; 14", 56, 57) defining respective optical resonance cavities (20, 22) for stimulated radiation of different wavelengths, which cavities include at least some common volume. Such means includes window means (13, 14) for emission of radiation amplified in the respective cavities. Means (15, 54) in one of said cavities is responsive to stimulated radiation emitted by a laser medium at one of the wavelengths to emit radiation at another of the wavelengths. Dual mode means (12, 54) has respective selectable first and second modes at which the laser cavity assembly is adapted to emit laser radiation predominantly at the respective wavelengths. Also disclosed are a novel Q-switch device and a combination laser oscillator and dual mode means.

Abstract: The present invention provides for multiple wavelength laser sources. The laser source has a pumping laser generating output at a wavelength, typically below 1500 nm, and a plurality of DBR fiber lasers or DFB fiber lasers, each having an output which is centered at a selected wavelength in the 1550 nm range. The fiber lasers are connected to the pumping laser such that the output light from said first pumping laser provides lasing energy for each of said fiber lasers. The fiber lasers may be connected serially or in series to each other. An optical fiber amplifier may be connected to the output of the serially-connected fiber lasers, or to the output of each one of the parallel-connected fiber lasers, to amplify the output from the fiber lasers so that the pumping laser provides energy for both the fiber lasers and the optical fiber amplifier.

Abstract: A semiconductor laser having a light amplifying diode heterostructure with a flared gain region in an narrow aperture end whoch may be coupled to a single mode waveguide and a wide output end. A light emitting surface of the heterostructure proximate to the wide end of the flared gain region is partially reflective and combines with an external reflector to form a resonant cavity that is effectively unstable. The intracavity light-emitting surface proximate to the narrow aperture end is antireflection coated. The external reflector may be a planar mirror or a grating reflector. A lens or an optical fiber may couple the aperture end of the flared gain region to the external reflector. Frequency-selective feedback is provided by orienting the grating reflector or providing a prism in the cavity in front of the external planar mirror. Other filtering elements may also be placed in the external cavity.

Abstract: A solid-state laser apparatus comprises a plurality of solid-state materials each having an active solid-state medium and arranged in a row with a predetermined space on an optical axis of light incident thereon. An optical rotation material and an angle adjusting instrument for adjusting an angle between the optical rotation material and the optical axis of incident light are disposed in at least a space selected from among the plural spaces. The laser apparatus further comprises a laser optical system for extracting a laser beam emitted by the plural solid-state materials.

Abstract: A laser includes a laser head and a power supply. At least two resonator mirrors define a resonator cavity. A gain medium is positioned in the resonator cavity. A temperature controller is positioned in the laser head and is coupled to the gain medium. The temperature controller maintains the gain medium at a temperature of 25 degrees C. or greater. A pump source supplies a pump beam to the gain medium and producing an output beam. The power source is coupled to the pump source.

Abstract: An optical unit for multiplying the frequency of a clock signal includes at least two series-arranged ring lasers. Each ring laser has a different resonance frequency f.sub.i. The unit has an input for receiving a signal, for example, a low-frequency electric signal for modulating one of the ring lasers. The repetition frequency of at least one of the ring lasers is variable by adapting the optical path length of the resonator.

Abstract: The invention provides a compactly built solid state laser, which can be pumped by high power semiconductor laser diodes and uses two or more laser crystals as the laser gain or amplification media, which crystals can also contain the resonator mirrors. As desired per the invention, linear, monolithic folded or ring-shaped laser resonators can be formed to provide very efficient production of frequency doubled laser radiation.

Abstract: A single longitudinal mode frequency-converted solid-state laser includes an optical pumping source that produces optical pumping radiation, a coupled resonant cavity having a first resonant cavity and a second resonant cavity sharing a common partially reflecting mirror, a solid-state laser medium disposed within the first resonant cavity and pumped by the optical pumping radiation, and an optical wavelength converting means within said second resonant cavity. The laser medium generates a first laser radiation at a first wavelength which is converted by the wavelength converting means into a second laser radiation at a second wavelength. A temperature controlling means controls the temperatures of the first and the second resonant cavities and of the optical pumping source. The optical path lengths of the first resonant cavity and the second resonant cavity are selected such that only one longitudinal mode of the coupled resonant cavity is within the gain bandwidth of the laser medium.

Abstract: Method for preparing a laser cavity resonator for use in a Raman gas analyzer, that resonator comprises a V-shaped housing which comprises a first and a second channel for the laser beam in a V-arrangement. The method allows the adjustment of the resonator in the manufacturing site and provides a high mechanical stability and reliability of the system and accelerates the manufacturing of the resonator. The resonator received by the method comprises adjusted mirrors fixed to the housing so that the resonator can be transported and installed in the analysis system at its place of application.

Abstract: A laser system capable of providing light of high intensity is disclosed. This system includes a laser gain medium and three reflectors. A first reflector and a second reflector spaced from the first reflector define a laser cavity that contains the laser gain medium. Light reflected by the first reflector is amplified by the laser gain medium. A third reflector is spaced from the second reflector to define a resonant cavity external to the laser cavity. Light passes from the laser cavity to resonate in the external resonant cavity. Part of the light passes from the external resonant cavity to the laser cavity. A light-screening device, e.g., an aperture, is disposed between the second reflector and the gain medium to screen light reflected from the external cavity such that the light portion of constructive interference is preferentially passed over the light portion of destructive interference. This enables the gain medium to optically lock to the resonant frequency of the external cavity.

Abstract: A diffusion-cooled laser has a lasing region shaped to provide a high power output laser beam of a high optical quality. The lasing region, which contains a lasing medium, has a narrow-aperture section and a free-space section. The narrow-aperture section is defined by resonator walls spaced apart a sufficiently small distance that enables effective excitation and cooling of the lasing medium. The free-space section is defined by resonator walls spaced apart a sufficiently larger distance that enables the laser beam to expand without restriction from the resonator walls in the free-space section. The narrow-aperture section enables the laser to generate a high power laser beam using a relatively low (40 MHz) ISM frequency. The free-space section allows the laser beam to expand sufficiently to exit the lasing region with a shape that is easily focused by inexpensive optical elements.

Abstract: A dual cavity laser having a positively mode-locked structure capable of double increasing the repetition rate of output light. The dual cavity laser includes an amplitude modulator to simultaneously generate two modulating signals with opposite phases. The dual cavity laser has a simply modified structure from that of the conventional single cavity laser to have two resonators, so that it can have a repetition rate corresponding to two times that of the single cavity laser. One of the resonators may have an adjusted optical property so as to obtain two kinds of output optical pulses with different optical properties.

Abstract: A distributed gain medium, such as an optical fiber, is configured as a Sagnac interferometer or loop mirror, and this mirror is used as at least one of the two reflectors in the amplifier or laser. The distributed gain medium produces optical signal gain through nonlinear polarization, that may cascade through several orders. The Sagnac interferometer or loop mirror defines two optical paths that will support both common mode and difference mode optical signals. Pump fluctuations resulting from higher cascade orders are at least partially rejected through the difference mode signal path, thereby reducing the overall effect of pump fluctuation. The result is a broadband optical resonator, suitable for use at a variety of different wavelengths, including 1.3 .mu.m and 1.55 .mu.m wavelengths. Amplifiers based on this technology are "four-level," providing a pass through signal even when the pump laser is not functioning.

Abstract: An autodyne lidar system utilizing a hybrid laser. The hybrid laser inclu a continuous wave (CW) optical gain section and a pulsed optical gain section in the same laser cavity. A highly reflecting mirror and a partially reflecting mirror, also called an output coupler, form the ends of a laser cavity. Both the continuous wave optical gain section and the pulsed gain section are positioned in the laser cavity. A detector is position in such a manner so as to observe the light reflecting through the cavity.

Abstract: An HBr laser is pumped by a slave laser power oscillator which excites the (2,0) absorption band of the HBr laser, to cause it to lase around four microns. A tunable master oscillator, which is frequency locked to an HBr reference cell, seeds the slave oscillator and maintains lock-on to an absorption line in the (2,0) band of HBr.

Abstract: A tunable laser produces laser emission at at least two wavelengths simuleously. The tunable laser includes at least two gain elements, where each gain element generates a different wavelength. Means for optically exciting each laser gain element is appropriately disposed for either end pumping or side pumping to produce a laser emission within a preselected range of wavelengths. A wavelength dispersing element such as a prism is disposed in the laser resonator cavity for dispersing the wavelengths operating simultaneously within the laser resonator cavity and to create separate regions for each laser gain element. Laser gain elements may be tunable laser gain elements or discrete emitting laser gain elements. Arbitrarily large wavelength separations between the wavelengths operating simultaneously may be achieved in this manner producing stable cw or pulsed output, Q-switched or line narrowed depending on the means disposed within the laser resonator cavity.

Abstract: Stability of a pump laser for activating an erbium amplifier is enhanced by a grating which results in laser operation in the coherence collapse regime.

Abstract: A multi-axial mode frequency conversion system includes two resonators. At least two resonator mirrors define a first resonator cavity. A gain medium is positioned in the first resonator cavity. A pump source supplies energy to the gain medium. The first resonator cavity produces a first beam with a plurality of axial modes that are incident on a doubling crystal in the first resonator and produce a frequency doubled output beam. The first resonator cavity provides a sufficient number of axial modes to oscillate so that the doubled output beam has a noise of less than 3% RMS. At least two resonator mirrors define a second resonator cavity coupled to the output beam from the first resonator cavity. The second resonator is configured to provide resonant enhancement of at least a portion of the plurality of axial modes. A non-linear optical material is positioned in the second resonator and configured to produce a harmonic output beam.

Abstract: Apparatus performs a method of generating one output laser pulses in a range of 2 to 5 microns using an intracavity feature. When a plurality of the output laser pulses are generated, a first output pulse may have any selected wavelength within the range and a second output pulse is temporally closely spaced relative to the first output pulse and may have a chosen wavelength differing from the selected wavelength. A pump laser cavity is provided with a tunable rod and an intracavity Raman device (in the pump cavity) to shift the wavelength of initial pump laser pulses. The intracavity Raman device generates radiation at first and second Stokes wavelengths, and the pulses at each wavelength are separated and are in separate paths for permitting separate operation thereon. The Raman device in the pump cavity increases the pump intensity inside the Raman cell and gives a much longer effective interaction length between the pump laser beam and the Raman medium.

Abstract: An optoelectronic semiconductor device with at least one laser and two mutually parallel, strip-shaped active regions, whose ends are optically coupled at one side, is a very suitable radiation source or amplifier, for example as a tunable radiation source. More than one kind of radiation is often present in such a device, whereas it is desirable for only one kind of radiation to pass through a gate of the device. To achieve this in prior devices, an additional component, such as a filter or isolator, is necessary.

Abstract: The apparatus of the present invention significantly improves the optical intensity induced damage limit of optical quality crystals, and in particular crystals used in the conversion of laser radiation at a specific wavelength to another wavelength or other wavelengths through non-linear interaction of the input laser radiation with the optical crystal medium. In accordance with the present invention, passive optical elements are positioned at the laser beam exiting and entrance surfaces of the active optical element. The surfaces of the passive optical elements are placed up against respective exiting and entrance surfaces of the active optical element. Since the optically transparent passive optical elements have higher mass than optical coatings, they provide vastly superior cooling, and therefore, considerably higher laser damage threshold for the surfaces.

Abstract: A laser system includes an apparatus having a primary laser resonator having a laser medium therein for producing a laser beam of a first wavelength and a second laser resonator optically connected to the primary resonator to allow a portion of the laser energy from the primary laser resonator to pass into the secondary laser resonator. An optical parametric oscillator is located intracavity of the secondary laser resonator and includes a nonlinear crystal for producing a laser beam of a second wavelength therefrom. A coherent beam output is coupled to the optical parametric oscillator for producing an output beam of predetermined wavelength of the second wavelength while blocking the output of the laser beam of the first wavelength so that a dual resonator combines a secondary laser cavity and an optical parametric oscillator to produce a predetermined output wavelength.

Abstract: The present invention relates to a passively Q-switched laser with a dual-cavity configuration to obtain a symmetrical laser pulse with a short and variable pulse width. The passively Q-switched laser comprises: a laser medium and a passively Q-switching medium; a cavity mirror capable of fully reflecting the respective wavelengths emitted from the laser medium and the passively Q-switching medium; a main cavity mirror composed of a dichroic mirror having non-reflective characteristics for the light emitted from the passively Q-switching medium and reflective characteristics for the light emitted from the laser medium with a reflectivity of 10% or more; and, an auxiliary cavity mirror composed of a dichroic mirror having non-reflective characteristics for the light emitted from the laser medium and reflective characteristics for the light emitted from the passively Q-switching medium with a reflectivity of 10% or more and capable of moving transversely against the laser beam.

Abstract: A pulsed solid state laser system is disclosed which utilizes a plurality of individual laser rods which are sequentially pumped and whose beans are combined into a single interleaved output bean. The individual laser rods are pumped at an average power level which is below that for maximum output power from each rod, thereby obviating the need for refrigeration cooling. A compact optical system is disclosed which permits a constant beam size even at different pump levels and other advantages. A compact cooling system is also disclosed.

Abstract: A blue laser source outputting a beam having a wavelength of approximately 460 nm. A first laser cavity is formed around a Nd:YAG gain medium generating a first light beam having a wavelength of approximately 1064 nm. A second laser cavity, at least partially coextensive with the first laser cavity is formed around a Tm:ZBLAN gain medium generating a second light beam having a wavelength of approximately 810 nm. A non-linear KTP crystal is provided intracavity to both the first and second laser cavities to mix the first light beam and the second light beam and output a third light beam having a wavelength of approximately 460 nm. One of the mirrors forming the first or second laser cavity is coated to output a laser beam having a wavelength of approximately 460 nm.

Abstract: A high power diode pumped laser is disclosed which has at least one resonator mirror and an output coupler. At least one laser crystal with strong thermal focussing properties is included. The laser includes at least one diode pump source supplying a pump beam to the laser crystal, producing a thermal lens in the laser crystal. The combination of the laser crystal, thermal lens, resonator mirrors and output coupler create a confocal-to-concentric resonator. An output beam is generated, which may be polarized. Further, a Q-switch may be included in the resonator, particularly when the laser crystal is Nd:YAG.

Abstract: An excitation system for a gas laser featuring a multiplicity of gain channels uses a resonant cavity to provide broad band RF power division and impedance matching to the multiplicity of gain channels. Integral anode and grid resonant tank circuits featuring positive feedback may be employed to provide a self-excited power oscillator having a very high power capability with good efficiency at low cost. A smaller and higher frequency multi-channel excitation system fabricated from stripline resonator elements may be used for driving small scale multi-channel lasers. A common optical extraction system features either a stable, an unstable, or a hybrid optical cavity mode, with phase-locked or non-phase locked output performance, achieved via external or self-injection.

Abstract: Two solid state laser structures are provided which are optimized for multimode operation. The first laser structure has a plurality of normal incidence optically transmissive surfaces in the laser cavity. The most reflective one of those normal incidence surfaces is disposed at the optical center of the laser cavity. The gain medium is centered in the subcavity defined by a cavity mirror and the optical center. In the second laser structure, there are no normal incidence surface in the laser cavity, and the gain medium is disposed at the optical center of the laser cavity. The laser structures are employed to construct erbium glass lasers which are not only optimized for multimode operation but also have effective cooling of the gain medium and minimized thermal lensing effect.

Abstract: A medical laser system is disclosed for ablating biological material. The system includes an Erbium:YAG gain medium capable of generating a pulsed output having a wavelength of 2.9 microns. The laser is optimized to generate a pulsed output having a repetition rate of at least 50 hertz and preferably at least 100 hertz. The output is delivered to the target tissue via an optical fiber. Preferably, a suction source is provided to aspirate the tissue as it is being ablated.

Abstract: A laser system capable of providing light of high intensity is disclosed. This system includes a laser gain medium and three reflectors. A first reflector and a second reflector spaced from the first reflector define a laser cavity that contains the laser gain medium. The second reflector has a reflectivity (R.sub.2) larger than the reflectivity (R.sub.1) of the first reflector such that light emitted from the laser gain medium resonates in the laser cavity. A third reflector having a reflectivity (R.sub.3) larger than the reflectivity of the first reflector (R.sub.1) is spaced from the second reflector to define a resonant cavity external to the laser cavity. Light passes from the laser cavity to resonate in the external resonant cavity. Part of the light passes from the external resonant cavity to the laser cavity to optically lock the laser gain medium.

Abstract: A medical laser system is disclosed for ablating biological material. The system includes an Erbium:YAG gain medium capable of generating a pulsed output having a wavelength of 2.9 microns. The laser is optimized to generate a pulsed output having a repetition rate of at least 50 hertz and preferably at least 100 hertz. The output is delivered to the target tissue via an optical fiber. Preferably, a suction source is provided to aspirate the tissue as it is being ablated. The erbium laser system provides accurate ablation with minimal damage to surrounding tissue.

Abstract: A semiconductor laser emits semiconductor laser light with TM-mode oscillation. The emitted semiconductor laser light is collimated by a first collimating lens, passes through a Brewster plate that is arranged so that the direction of Brewster plane's p-polarized light is in alignment with the direction of polarization of the emitted semiconductor laser light, and is coupled to an incident portion of a wavelength-conversion waveguide by means of a focusing lens. While being guided through the waveguide, the emitted semiconductor laser light is converted into second-harmonic light by means of a polarization inversion region. Semiconductor laser light emanating from an emitting portion of the waveguide reflects from an output mirror towards a diffraction grating, for modulation in wavelength. Second-harmonic light emanating from the emitting portion of the waveguide is outputted from the output mirror.

Abstract: A waveguide carbon dioxide (CO.sub.2) laser includes a six-sided laser block comprising first and second triangular end sections and a rectangular insert block. The two triangular end sections include a waveguide grid comprising two sets of parallel waveguide channels intersecting at right angles and optically coupled by strip mirrors disposed along the edges of the triangular sections. The rectangular insert block also includes a set of parallel waveguide channels which are congruent with and aligned parallel to the waveguide channels of the two triangular end sections, thereby extending the cavity length of a multiply folded waveguide laser without a corresponding increase in the number of optical folds, the number of folding mirrors, or the value of distributed loss.

Abstract: A laser system includes an apparatus and method having a primary laser resonator having a laser medium therein for producing a laser beam of a first wavelength and a second laser resonator optically connected to the primary resonator to allow a portion of the laser energy from the primary laser resonator to pass into the secondary laser resonator. An optical parametric oscillator is located intracavity of the secondary laser resonator and includes a non-linear crystal for producing a laser beam of a second wavelength therefrom. A coherent beam output is coupled to the optical parametric oscillator for producing an output beam of predetermined wavelength of the second wavelength while blocking the output of the laser beam of the first wavelength so that a dual resonator combines a secondary laser cavity and an optical parametric oscillator to produce a predetermined output wavelength.

Abstract: A passively controlled multiple output fiber laser system in which the frequency relationships between all of the optical outputs remain constant over time includes a plurality of fiber lasers for generating respective output beams. The lasers are positioned in close proximity to each other so that they experience the same environmental conditions. Each laser includes at least one Bragg reflection grating that controls the frequency and bandwidth of the laser's output beam. The Bragg gratings are formed so that they respond equally to environmental changes. In a preferred embodiment, the fiber lasers are made from a plurality of substantially identical photosensitive fibers, and Bragg gratings are exposed simultaneously under identical exposure conditions in each of the fibers. A multiple output fiber laser system suitable for heterodyne LADAR systems is also provided.