Abstract: An apparatus and method are provided for converting a pump laser beam having a first wavelength to an output beam of a second wavelength. The wavelength conversion device includes a solid medium impregnated with dye laser which is rotated at a speed which is slow enough to allow the dye material to lase and fast enough to reduce thermally induced optical aberrations and triplet state absorption. The medium and method provide a variety of output laser wavelengths suitable for treating diseases of the eye. In the preferred embodiment, the medium has the dimensions of a standard compact disk.

Abstract: A photonic crystal fiber (10, 110) is provided for a laser/amplifier system including a guiding structure comprising a geometric array of axial passages (20, 120) formed along the length of the fiber (10, 110). More particularly, the guiding structure includes a central silica rod (14, 114) which is doped with a rare earth element for providing optical gain to the laser/amplifier. A plurality of second silica rods (16, 116) are disposed circumferentially about the central rod (14, 114). Each of the second rods (16, 116) includes an axial passage (20, 120) formed therethrough along the length of the fiber (10, 110). A reflective coating (22, 122) is deposited on an outboard surface of the array of rods (12, 112) to confine pumped light (30, 130) therein.

Abstract: It is an object of this invention to overcome the problems of prior art by a unique arrangement based on a novel idea, and to provide an optical device having desired characteristics and an optical module and optical system incorporating the optical device.

Abstract: According to the invention, the active element for a laser source comprises an elongate rod comprising a doped matrix capable of absorbing a pump beam in order to amplify laser radiation propagating longitudinally, at least one input face for the pump beam, a first reflection face for the pump beam which is inclined with respect to the longitudinal axis of the rod and at least one interacting second reflection face, at least one of the input face and second reflection face being equally inclined.

Abstract: A wafer assembly that includes a wafer substrate. A plurality of micro-optomechanical or micro-optoelectrical devices are positioned on a surface of the wafer substrate. Each micro-optomechanical or micro-optoelectrical device has a seal surface. A plurality of seal caps are coupled to the micro-optomechanical or micro-optoelectrical devices. Each seal cap has a seal ring. The seal cap seal ring is coupled to a seal surface of the micro-optomechanical or micro-optoelectrical device to form a hermetic seal.

Abstract: A multi-pass, integrating diode pump cavity for an Er,Yb:glass laser is provided. The diode pump cavity comprises two end members of undoped glass sandwiching a center section of glass of the same composition as that of the two end members but doped with erbium and ytterbium ions. The two end members are each provided with a curved outer surface, which is coated with a reflective coating. At least one of the curved surfaces includes a slit through the reflective coating for transmission of pump laser light from a pump diode laser bar into the cavity. The diode pump cavity is small, compact, efficient, and eye-safe.

Abstract: A microlaser is provided that has a microresonator and a pump source for side pumping the microresonator. The microresonator includes an active gain medium and a Q-switch that extend lengthwise between the opposed end faces of the microresonator. The pump source is therefore positioned so as to introduce pump signals into the microresonator via the side surface that is adjacent to and defined by the active gain medium. By side pumping the microresonator, the microlaser can generate a series of pulses having greater pulse energies and greater average power levels than the pulses provided by conventional microlasers. In addition, the side pumped microlaser can also generate pulses having greater pulse widths than the pulses provided by conventional microlasers of a similar size.

Abstract: A diode array (32) which includes a diode bar (22) having a plurality of laser diodes (42) within an active region (40) so as to emit light parallel to an optical axis (26), generally parallel to the laser diodes (42). The diode bars (22) are sandwiched between a pair of spacer layers (34, 36). Each spacer layer (34, 36) includes two or more spacers (48, 50). The spacers (48, 50) in each layer (34, 36) are configured such that gaps (52, 54) between contiguous spacers (48, 50) are at a non-parallel angle (&THgr;) relative to the optical axis (26) of the diode bar (22). By orienting the gaps (52, 54) between the spacers (48, 50) at non-parallel angle relative to the optical axis (26) of the laser diodes (40), the gaps (52, 54) span several laser diodes (40), thus averaging any inhomogeneous effects caused by the gaps (52, 54) resulting in a relatively more uniform output from the various laser diodes (40) forming the diode bar (22).

Abstract: A solid state laser has an elongate slab of lasing material having a rectangular cross section with the lower face of the slab contacting a slab mount which is of a high thermal conductivity material. Energy to drive the lasing medium is provided by a flash lamp. Upper and lower faces of the slab are polished to an optically smooth finish so that light is able to propagate in a generally axial direction through the slab. Side faces of the slab are polished and then re-roughened to provide a finish with a surface damage zone comparable in depth to the wavelength of the lasing emission. For a lasing wavelength of one micrometer, the depth of surface damage is in the region of one micrometer.

Abstract: An optical device includes a light transmitting non-linear optical material having a first face and a second face. The first and second faces oppose each other. The first face has a plurality of first reflecting portions provided thereon, and the second face has a plurality of second reflecting portions provided thereon. Each of the second reflecting portions corresponds to one of the first reflecting portions. Furthermore, the first and second faces are substantially flat except for at least one convex arcuate portion being formed on at least one of the first and second faces. Additionally, at least one of the first and second reflecting portions is obtained by coating a reflective material on the convex arcuate portion.

Abstract: A resonant absorption cell filled with a gas, selected in accordance with the wavelength of the laser radiation of interest, such as DF. The gas within the cell is maintained at substantially atmospheric pressure. The energy state of the gas within the cell is raised by either external resistance heating or optical pumping. In an increased energy state, gas molecules resonate with the incoming laser radiation causing the molecules to absorb incident photons before the gas molecules have a chance to re-radiate the captured photons, collisions with other gas molecules within the cell transfer the excitation energy into heat in order to filter out laser radiation but past all other wavelengths.

Abstract: The present invention relates to apparatus for providing orthogonally polarized light beams for use in precision metrology applications such as in the measurement of length or length changes using interferometric techniques. An input beam is introduced to a multifaceted anisotropic optically active acousto-optical crystal for travel through an interactive region where it experiences two acoustic beams that diffract it via small angle Bragg diffraction to form two orthogonally polarized internal beam components that are separated by a small angle of divergence and subsequently become external beam components available outside of the acousto-optical crystal for use in anticipated downstream applications. The acousto-optical crystal preferably is a uniaxial crystal comprising TeO.sub.2.

Abstract: A laser to produce pulses of light having predetermined spectral shapes, comprising a waveguide, an optical pump source, a gain medium to produce seed radiation, and a modulator and an array of Bragg gratings to modify the properties of the seed radiation. Once generated by the gain medium, the seed radiation propagates in the waveguide where it is first pulsed by the modulator. The resulting pulses are then selectively reflected by the Bragg gratings, which separates different spectral components of the reflected beam. This reflected beam then travels back to the modulator, which is timed to let only the desired spectral components go through. In this manner the laser is self-seeded and allows spectrum and wavelength selection from pulse to pulse.

Abstract: A light amplification device comprises a laser slab and optics for establishing an optical beam at the lasing wavelength. The beam travels inside the slab in a zig-zag path between two reflecting faces. The slab is also cooled through the reflecting faces. The slab is pumped through one or more pumping faces, each pumping face being distinct from the reflecting faces. Light from the pump is incident upon the slab in a direction that is transverse to the plane of propagation of the lasing wavelength beam. This arrangement separates the cooling interfaces from the pumping interfaces. Distortions in the beam due to thermal effects are largely averaged out by the zig-zag path. The device may function as either a laser or an optical amplifier.

Abstract: A total-internal-reflection thermally compensated rod laser including a lasing rod composed of crystalline or glass material doped with at least one lasing ion. The rod has an optical axis, an axially extending, substantially optically flat, exterior surface, and a substantially optically flat conical surface at each end. Both conical end surfaces are coaxial with the optical axis and has a truncated tip. The first end has a convex surface and the second end has a concave surface. The rod has a geometry, including a diameter and a length, selected to provide substantially no net depolarization of an incident beam.

Abstract: A dye laser for generating laser pulses of long duration comprising an optic resonator which comprises an elongated dye cell, which contains light gain medium that can be excited to population inversion, the outputs of the laser pulses from the dye cell being formed of the end surfaces of the cell. There are mirrors placed in optical connection with the outputs of the laser pulses of the dye cell, at least one of the mirrors being partially transmissive for feeding the laser pulse out. Furthermore, means comprising at least one elongated gas discharge lamp are arranged in the longitudinal direction of the dye cell to feed excitation light into the dye cell so that the excitation light sweeps across the cell in the lateral direction of the cell.

Abstract: A unidirectionally operating laser apparatus using a semi-monolithic ring cavity having a compact structure capable of achieving a high frequency stability and a high-speed laser frequency tuning and modulation. The laser apparatus includes a laser active medium having a curved surface exhibiting an anti-reflection characteristic for a pump laser beam from a pump laser incident thereon while exhibiting a high reflection characteristic for an oscillating laser beam, a planar surface exhibiting an anti-reflection characteristic for the oscillating laser beam, and an optically-active polarization rotator attached to one side portion of the planar surface. The laser apparatus also includes an output mirror separated from the laser active medium, the output mirror having a curved surface with a coating exhibiting a higher reflectance coefficient for S-polarized beams than that for P-polarized beams, and a piezo-electric transducer.

Abstract: A light amplifier device comprises an amplifier medium plate consisting of an upper part comprising two lateral faces (11) and (12) and a lower part comprising two lateral faces (13) and (14), the lateral faces (11) and (13) being located on a first face of the amplifier medium, the lateral faces (12) and (14) being located on a second face of the amplifier medium opposite said first face, at least two light beams (2) and (2') amplified by the amplifier medium and optical pumping means of said amplifier medium, wherein the light beam (2) is introduced into the amplifier medium at a lateral face (11) or (12) and the light beam (2') is introduced into the amplifier medium at a lateral face (13) or (14). The faces (11) and (12) are antiparallel to each other, the faces (13) and (14) being also antiparallel to each other. Application to power lasers.

Abstract: A semiconductor optical amplifier which has a good extinction ratio and a simple structure includes an optical waveguide having at least a curved portion. The optical waveguide has light input and output ends offset from each other to keep optical fibers out of alignment with each other at respective opposite ends of the optical waveguide.

Abstract: An optical device includes a block of optical material. The block includes a first and second end face, and a portion of the first end face includes at least one convex arcuate portion.

Abstract: A solid state saturable absorber (SSSA) is formed from a slab of solid state material, such as Cr.sup.4+ : YAG. Optical distortion caused by the absorption process can be minimized by confining absorption to portions of the solid state slab which can be cooled efficiently. In accordance with an important aspect of the invention, the use of the SSSA in accordance with the present invention allows the repetition rate, pulse width, and energy level of the laser output pulses to be controlled by way of optical pump sources, such as a diode array. The solid state slab material allows for zig-zag propagation and thus, averaging of the thermal gradients caused by absorption, optical pumping and cooling which results in relatively low thermal lensing with virtually no birefringence and therefore allows for passive Q-switching applications in relatively high brightness laser systems.

Abstract: A surgical laser system is provided with improvements to allow it to operate at higher power levels without beam divergence. The improvements include a beam expansion telescope in the optical path of the beam and modifications to the optical cavity and the lasing medium. The modifications include imposing a negative curvature on one or both ends of the rod, configuring the optical cavity as a positive-branch unstable resonator, and providing at least one intra-cavity shutter.

Abstract: A photonic light emitting device comprising a relatively high refractive index photonic-wire semiconductor waveguide core in the form of an arcuate shape, linear shape and combinations thereof. The waveguide core is formed into a closed loop cavity for a light-emitting device or laser. The waveguide core is surrounded on all transverse sides by relatively low refractive index medium and comprises an active medium having major and minor sides and semiconductor guiding layers proximate the major sides. The active medium and the guiding layers are so dimensioned in a transverse direction relative to the path of light propagation through the core to provide dramatically increased spontaneous-emission coupling efficiency, leaading to low lasing threshold and high intrinsic modulation rates.

Abstract: An access system based on piezo-electric transducer assembly or electro-optic device light beam deflector assembly which on application of electric signals deflects light beams, which are then passed through total internally reflecting surfaces to increase the separation between beams, is described. The light beams fall on large area information storage surface, such as optical disk or magnetic disk, for the purpose of reading and writing. The access time to the information is very fast. The nature of the reflected light from the memory surface is detected to read the digital signals stored on the surface as is conventionally done in the art. Except for the small friction-free movements of the piezo-electric transducers there are no moving parts for access to the storage surface. Instead of the memory surface a screen may be placed when tthe light beams can be used after large separation to form a fast display.

Abstract: A third-harmonic crystal has a Brewster-cut dispersive output surface for separating the p-polarized fundamental and third-harmonic beams without introducing losses into the beams. The output surface of the third-harmonic crystal is optically uncoated, and thus insensitive to potential ultraviolet (UV)-induced damage. Frequency doubling and tripling lithium triborate (LBO) crystals are used with a Brewster-cut Nd-YAG active medium in a resonant cavity to generate UV light at 355 nm from infrared (IR) light at 1064 nm. Except for the tripling crystal output surface, the doubling and tripling crystal optical surfaces are normal-cut and anti-reflection (AR) coated.

Abstract: An optical element providing greater conversion efficiency and comprising a pyramid having a square base and four triangular faces of equal size and shape meeting at the apex. The optical element can also comprise an octahedron or double pyramid of similar configuration.

Abstract: Laser comprising a first lasing microdisk, microcylinder or microannulus defining a microcavity having a circular cross-sectional periphery and a second waveguiding micromember spaced from the first lasing micromember in a different plane and optically coupled by resonant photon tunneling. The second waveguiding micromember includes a light output coupling for providing light output from the laser without adversely affecting the Q value and low lasing threshold of the microcavity.

Abstract: A variable power laser device includes a lasing medium having first and second end faces disposed parallel to one another, N side faces extending between the first and second end faces and a bevel face located at an intersection between the second end and one of the side faces, a first mirror separate from the first end face for directing a laser beam into the lasing medium so as to permit the laser beam to follow a helical transmission path defined by the N side faces, the transmission path being longer than the length of any of the N side faces, and a second mirror separate from the second end face for receiving an amplified laser beam output by the lasing medium and reflecting the amplified laser beam in a predetermined direction, wherein N is an integer greater than or equal to 3. The output power of the amplified laser beam is dependent on the number of loops in the transmission path.

Abstract: A p-Ge laser operating at submillimeter wavelengths in Voigt configuration using a regular permanent magnet. The invention is improvement over prior art Ge Lasers which use superconducting magnets that require liquid helium to cool the magnets along with the Ge crystal. Although the subject invention requires cooling(refrigerant) of the Ge crystal itself, it does not need liquid helium. The permanent magnet can be Nd.sub.2 Fe.sub.14 B. The emissions using the novel invention were observed over a wider range of electric-field magnitude in Voigt configuration at a given magnetic field as compared to that of the prior system. The free space beam profile of the subject invention is Gaussian. The emission-strength of the subject invention is sufficient between 4 and 10K that a closed-cycle refrigerator can be used to cool the crystal rather than the liquid helium used in all prior p-Ge lasers.

Abstract: A transversely pumped solid state laser includes: a solid state gain medium having thickness, width and longitudinal dimensions; means for forming a laser cavity with the medium for generating a laser beam along the longitudinal dimension; and a semiconductor laser pump source for directing a collimated pump beam to the medium along the width dimension transversely to the longitudinal dimension constrained toward the center of the medium and having a width which is substantially shorter than the longitudinal dimension of the medium for spacing the edges of the collimated beam away from the longitudinal ends of the medium to reduce thermomechanical distortion of the longitudinal ends of the medium and consequent distortion of the laser beam.

Abstract: A high-Q pump cavity is formed from undoped crystal pieces that are diffusion bonded to a doped core of the same crystal host material. The resulting monolithic pump cavity has 2 opposing convex-curved sides which have a highly-reflective coating on their outer surfaces, except in narrow slit-shaped areas on each curved side through which laser-diode-supplied pump light enters the cavity. The curvature of the two curved sides is such that nearly all the pump light rays that pass through the slit-shaped areas are focussed by the curvature onto the doped core, and rays that enter the cavity are redirected through the doped core many times, resulting in efficient, uniform absorption. The cavity has two opposing flat sides that interface with metal heat sink blocks to facilitate the removal of internally-generated heat. Thermally induced astigmatic lensing caused by this heat is countered by cavity design in which the core shape and the dimensions of the cavity minimize this astigmatism.

Abstract: A monolithic diode pumped solid-state laser (11) comprising as the laser host neodymium-doped yttrium orthovanadate (Nd:YVO.sub.4) (12, 52) or neodymium-doped gadolinium orthovanadate (Nd:GdVO.sub.4) (57, 67) operating on the .sup.4 F.sub.3/2 .fwdarw..sup.4 I.sub.9/2 (.about.914 nm or .about.912 nm respectively) transition, to which a suitable nonlinear optic material (16), such as potassium niobate (KNbO.sub.3) or beta barium borate (BBO), is bonded. The nonlinear crystal gives rise to intracavity frequency doubling to .about.457 or .about.456 nm. The microlaser is a composite cavity formed from a gain medium crystal and a nonlinear frequency doubling material which together have four spaced parallel dielectrically coated faces (14, 17, 18, 15) and which is positioned in close proximity to a diode laser pump source (13) for phase-matched harmonic generation of blue light along an axis of propagation which lies substantially perpendicular to the two faces of the composite cavity.

Abstract: A laser apparatus includes a hollow cylindrical solid state laser medium and an optical resonator having reflective surfaces at each end of the laser medium in the axial direction of the laser medium for causing a light emitted into the laser medium to travel back and forth along the elongated axial direction of the laser medium. One of the reflective surfaces of the optical resonator is shaped to reflect the beam at an angle to the beam impinging thereagainst to thereby walk the beam tangentially around the hollow cylindrical solid state laser medium at a fixed radial distance from the elongated axis of the laser medium. An exit slot is formed in one of the reflective surfaces. A pumping means for exciting the laser medium includes at least one flashlamp positioned adjacent the laser medium along the laser medium axis through the hollow cylindrical portion of the laser.

Abstract: An upconversion laser material includes a micro-sphere which is doped with an ion of a rare earth element and made of one selected from the group consisting of crystals and glasses. Thus, the micro-sphere achieves the light confinement therein and serves as a resonator. Therefore, the Q-value of the resonator becomes large. With this, it is possible to obtain the upconversion laser oscillation at room temperature.

Abstract: A composite multiple wavelength laser material is provided and is typically constructed with a common axis of construction in the form of a rod of uniform cross-section. The rod comprises a plurality of segments of laser material bonded, e.g., diffusion bonded, to one another along the common axis. Each segment lases at a unique wavelength when excited to produce a laser emission. The segments can be made from a birefringent material doped with laser active ions. If the same birefringent host material is used for all segments, ground-state absorption losses can be reduced by terminating either end of the rod with end segments made from undoped pieces of the birefringent material.

Abstract: This invention relates to a diode pumped slab laser in the form of a slab where two opposite faces are adapted to receive pumping radiation with the faces being cut at the Brewsters angle at one end to provide entrance/exit faces for the lasing radiation. The laser radiation beam follows a zig-zag path in the slab and is contained within the slab by total internal reflection. The laser slab is contained within an optical cavity which results in the laser beam completing a double zig-zag beam path. The design results in good pump/mode matching, mitigates thermally induced birefringence problems, overcomes amplified spontaneous emission problems, requires no coatings or curved surfaces, and is easy and relatively inexpensive to make. The slab can be used within both Quasi-CW and CW modes.

Abstract: A microfine light source is provided by a non-spherical particle containing a dye, which is irradiated with a laser beam under conditions that the particle emits light at a plurality of frequencies. A micromemory sensor which employs the light confinement properties of these non-spherical particles is also provided. The microfine light source is applicable to new physical and chemical processes, the processing and modification of particles, and to photon STM.

Abstract: A laser apparatus of the end pumping kind in which an elongated transparent laser element is mounted in spaced relationship within a tubular waveguide which has a highly reflective inner surface. The arrangement is such that, at least along part of the laser element, the optical distances between different points on the surface of the laser element and the inner contour of the waveguide vary.

Abstract: A solid state laser apparatus includes a laser medium of a uniaxial crystal, such as a fluoride crystal, having a negative temperature variation ratio of refractive index, laser diodes for optically pumping the laser medium, a set of mirrors positioned at two longitudinal ends of the laser medium for oscillating the light in the laser medium and outputting a beam, and a system for cooling the laser medium. The thermal lens effect is suppressed by causing a thermal gradient to exist along only one chosen axis of the laser medium and eliminating the thermal lens diopter along the chosen axis by optimizing a ratio L/D of length L and diameter D of the laser medium.

Abstract: A monolithic diode pumped solid-state laser (11) comprising as the laser host neodymium-doped yttrium orthovanadate (Nd:YVO.sub.4) (12, 52) or neodymium-doped gadolinium orthovanadate (Nd:GdVO.sub.4) (57, 67) operating on the .sup.4 F.sub.3/2 .fwdarw..sup.4 I.sub.9/2 (.about.914 nm or .about.912 nm respectively) transition, to which a suitable nonlinear optic material (16), such as potassium niobate (KNbO.sub.3) or beta barium borate (BBO), is bonded. The nonlinear crystal gives rise to intracavity frequency doubling to .about.457 or .about.456 nm. The microlaser is a composite cavity formed from a gain medium crystal and a nonlinear frequency doubling material which together have four spaced parallel dielectrically coated faces (14, 17, 18, 15) and which is positioned in close proximity to a diode laser pump source (13) for phase-matched harmonic generation of blue light along an axis of propagation which lies substantially perpendicular to the two faces of the composite cavity.

Abstract: This invention relates to solid state lasers and more particularly to laserable rods, slabs or other configurations where thermal effects and/or ground state absorption cause a degradation in lasing efficiency and/or beam quality. The improvement in operating efficiency is achieved by using a composite of lasing and non-lasing sections. The composite is formed using diffusion bonding techniques.

Abstract: A solid-state laser architecture producing a beam of extremely high quality and brightness, including a master oscillator operating in conjunction with a zig-zag amplifier, an image relaying telescope and a phase conjugation cell. One embodiment of the laser architecture compensates for birefringence that is thermally induced in the amplifier, but injects linearly polarized light into the phase conjugation cell. Another embodiment injects circularly polarized light into the phase conjugation cell and includes optical components that eliminate birefringence effects arising in a first pass through the amplifier. Optional features permit the use of a frequency doubler assembly to provide output at twice optical frequencies, and an electro-optical switch or Faraday rotator to effect polarization angle rotation if the amplifier material can only be operated at one polarization.

Abstract: A multiform crystal 10 suitable for laser applications is described. The multiform crystal 10 comprises at least two single crystal segments 12 fused together with a joint 14 therebetween, the joint being substantially optically transparent to light propagating through the crystal 10. The multiform crystal 10 is formed by polishing two single crystal segments 12 to form at least one optically flat face on each segment. The polished faces are cleaned and contacted against one another to form a joint 14 between the crystal segments 12. Substantially all the oxygen in the joint 14 is removed. The joint 14 is maintained at a sufficiently high temperature and pressure to join the segments together at the joint forming the substantially optically transparent joint 14. Mounting fixtures suitable for holding the crystal segments 12 firmly against one another in a furnace, without causing undesirable thermal expansive forces to be exerted on the segments 12, are also described.

Abstract: Apparatus for extracting heat from objects such as a slab laser having an accessible flat surface subject to being heated and including a flat strip of material, preferably made from wafer grade semiconductor, such as silicon or gallium arsenide, and mounted in close proximity to the surface so as to leave a small gap therebetween of uniform thickness over an area of said surface to be cooled. A still gas fills the volume of the gap which is sufficiently small that the gas serves as an effective heat transfer medium from said surface to said strip from which heat is transferred to a medium mounted in thermal contact with the strip on the side away from said surface being cooled. The invention has particular application to the cooling of slab lasers.

Abstract: There is described a semiconductor microcrystallite doped glass that exhibits SHG, and a method of preparing, or encoding, a semiconductor microcrystallite doped glass by the simultaneous injection of fundamental and second harmonic fields, such as 1.06 .mu.m and 532 nm. More specifically, the disclosure pertains to a structure that exhibits SHG, the structure being comprised of, by example, borosilicate glass that contains CdS.sub.x Se.sub.1-x microcrystallites. Also disclosed are embodiments of devices having an optical waveguide structure formed within a glass substrate that contains semiconductor microcrystallites. The optical waveguide structure guides and contains injected radiation and also converts a portion thereof to the second harmonic. Also disclosed are optoelectronic devices that include frequency doublers, self-doubling lasant material, bichromatic optical switches, and a volume holographic medium, all of which include a glass host having semiconductor microcrystallites embedded within.

Abstract: In an optical amplifier for amplifying a signal light by propagating the signal light and a pumping light in a rare earth element doped fiber doped with a rare earth element, a diameter of a rare earth element doped portion of the rare earth element doped fiber is gradually reduced in a direction of propagation of the pumping light. With this construction, an adverse rare earth element doped area which does not contribute to optical amplification, but rather attenuates the pumping light, can be eliminated to thereby provide an optical amplifier having increased amplification efficiency.

Abstract: A very compact source of laser radiation in the visible is described which uses pulsed laser diode on which is mounted a thermal transfer block having an arm for receiving the diode, and another arm for receiving a laser cavity comprising of a slab of Nd--YVO.sub.4, a second harmonic crystal such as KTP, one surface of which becomes the output coupler of the visible radiation, and one aspheric end mirror.

Abstract: A high temperature laser assembly capable of withstanding operating temperatures in excess of 1500.degree. C. is described comprising a segmented cylindrical ceramic lasing tube having a plurality of cylindrical ceramic lasing tube segments of the same inner and outer diameters non-rigidly joined together in axial alignment; insulation of uniform thickness surround the walls of the ceramic lasing tube; a ceramic casing, preferably of quartz, surrounding the insulation; and a fluid cooled metal jacket surrounds the ceramic casing.

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 protective coating [26] and a method for applying the same on an optically pumped solid state laser [10] having a lasing medium in the form of a slab [12] with at least two opposed parallel pumping faces [18, 20] between which a laser beam [11] propagates along a zig-zag path dictated by total internal reflection between these pumping faces. The slab [12] has an input face [14] for coupling in the laser beam and an output face [16] for coupling it out. The protective coating [26] is an organic synthetic, processed thermoplastic, or thermosetting polymer. Preferred materials include polymethylmethacrylate (PMMA), polyvinylidene chloride (PVC), polyethylene, polyimide, and Mylar.The protective coating [26] is applied onto the slab [12] from a solution in which the solvent is selected from the group of materials consisting of ketones, esters, and perfluorinated solvents.