Abstract: A solid-state laser in which a rod (10) of lasing material is held within an optical cavity formed within a cooling block (40) having a highly surface facing the rod. A longitudinal slit (44) formed in the block from the optical cavity to the outside allows the pumping light from an emission line (36) of semiconductor stripe lasers (30) fabricated on a laser bar (28) to irradiate the laser rod and multiply reflect within the optical cavity. Thereby, pump light is efficiently absorbed by the laser rod, and the laser rod is thermally controlled. Alternatively, cooling liquid (124) can flow axially along the laser rod and within an axially extending optical cavity formed by a reflective coating (125) deposited on a tube (122) enclosing the cooling liquid and having a slit (126) through which pump light is irradiated.

Abstract: A laser system in which an intense laser beam of a predefined pumping wavelength traverses a non-linear material, such as crystalline lithium niobate, that has been impressed with one or more quasi phase matching (QPM) gratings is disclosed. Quasi phase matching compensates for the dispersion or birefringence in a non-linear material by modulating the non-linearity with the proper period such that the different wavelengths involved in the non-linear process stay in phase over a long interaction length. The first QPM grating promotes the parametric generation of a resonant signal whose wavelength is determined by the grating period. According to the invention, either a second QPM grating impressed in the same medium or a different order of the first QPM grating promotes the non-linear interaction between the resonant signal and another optical signal traversing the non-linear material.

Abstract: A stabilized solid-state laser in a thermal imaging system in which a laser diode pumps the solid-state laser and a modulator modulates the laser beam according to graphical data to be recorded in a thermally sensitive medium, as is used in the graphics industry. The solid-state laser is stabilized against relaxation oscillations induced in the laser by modulated light reflected back from the thermally sensitive medium. The light reflected from the medium is allowed to reenter the solid-state laser, but the optical output of the solid-state laser is sampled in the frequency band in which relaxation oscillations occur. The detected intensity is then used in a feedback circuit to control the intensity of the diode laser that is optically pumping the solid-state laser. Thereby, the data modulation does not cause the solid-state laser to oscillate, and neither a Faraday rotator nor use of a diffracted beam is required.

Abstract: A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A confocal resonator or White Cell resonator is provided, including two or three curvilinearly shaped mirrors facing each other along a resonator axis and an optical gain medium positioned on the resonator axis between the mirrors (confocal resonator) or adjacent to one of the mirrors (White Cell). In a first embodiment, two mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator.

Abstract: A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A resonator or a White Cell cavity is provided, including two or more mirrors (planar or curvilinearly shaped) facing each other along a resonator axis and an optical gain medium positioned on a resonator axis between the mirrors or adjacent to one of the mirrors. In a first embodiment, two curvilinear mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator.

Abstract: A laser material for a solid-state laser that, when pumped by light having a wavelength in a suitable pump band, emits electromagnetic radiation having a wavelength lying in the range 2.0.ltoreq..lambda..ltoreq.2.1 .mu.m. The laser host material includes thulium-doped lutetium yttrium aluminum garnet (Tm:LuYAG) of approximate chemical composition (Tm.sub.x (Y.sub.w Lu.sub.1-w).sub.1-x).sub.3 Al.sub.5 O.sub.12, with x lying approximately in the range 0.01.ltoreq.x.ltoreq.0.5 and w lying in the range between 0.01 and 0.99. In particular, the Tm:LuYAG material produces light with wavelengths in the range .lambda.=2.020-2.024 .mu.m, where the normally-absorbing atmosphere has a transmission window with markedly reduced (or, alternatively, markedly enhanced) absorption. Another suitable group of laser materials has the chemical composition (Tm.sub.x (Y.sub.w Lu.sub.1-w-z Sen.sub.z).sub.1-x).sub.3 Al.sub.5 O.sub.12, with x lying approximately in the range 0.01.ltoreq.x.ltoreq.0.5, w lying in the range 0.01.ltoreq.

Abstract: Compact solid state laser apparatus that includes a laser diode pump, beam forming optics, a laser gain medium and optical resonator, a photodetector to vary the power supplied to the laser diode pump to suppress relaxation oscillations that might otherwise appear in the laser gain medium output light beam, an optical isolator and laser output optics. Each of the optical components has an independently activatable heater to allow optical alignment of that component. Each of the laser diode pump and laser gain medium has an independently activatable thermoelectric cooler to allow optical alignment (laser gain medium only) and to provide thermal tuning of the output wavelength of that device. An optical platform, which is thermally conductive, electrically non-conductive and has low thermal expansion, supports the other components, provides a substrate for electrical traces that provide power for operation of the apparatus and contains the heaters for the optical components.

Abstract: Apparatus for end-pumping of a solid-state laser with a source of high optical brightness. A stack of diode laser bars are excited, and each bar emits a light beam of a selected pump wavelength in a chosen direction. The light beam output of the diode bar stack is divided into a plurality of smaller, approximately rectangular light beams, which serve as extended light sources, by a plurality of mirrors that are positioned to receive one or more of these smaller beams and redirect such beams onto first, light-receiving ends of one or more optical fibers. Light collection optics receive the beams issuing from the mirrors and focus these beams onto a light-receiving end of an optical fiber with beam convergence angles that are appropriate for the numerical aperture of that fiber.

Abstract: Apparatus for providing a laser light beam or an amplifier light beam that is scalable to very high light beam output power by use of approximately identical optical sections, each section containing one or more laser gain media and one or more fold mirrors, spaced apart from the laser gain media by a distance d. The laser gain media or the fold mirrors, or both, have a curved reflecting surface of radius R. The lengths d and R are chosen to provide a stable optical system within each optical section and to compensate for the development of a thermal lens within each laser gain medium when this medium is pumped by a light source. The optical sections may be concatenated to scale the light beam output power upward without limitation, except for optical absorption and losses that occur at each reflecting surface.

Abstract: Method and apparatus for stabilization of pulse energies produced by a continuously pumped, Q-switched, solid-state or gas laser, through control of the optical power delivered by an optical pump to the laser, in order to limit the energy emitted in any single laser pulse as a result of Q-switching. The laser pump is driven at full strength for a selected initial refresh time t.sub.r. If a Q-switch trigger signal is received by the laser before the elapsed time .DELTA.t has reached the refresh time t.sub.r, the laser emits a pulse with the reduced energy stored in the laser at that time. If the elapsed time reaches or exceeds the refresh time t.sub.r, the optical pump power subsequently delivered to the laser is reduced to a lower level, which may be time-dependent, that is sufficient to maintain the net energy stored in the laser at a predetermined value so that the energy in a subsequently emitted laser pulse does not exceed a selected limit.

Abstract: A miniature laser cavity in which a solid-state lasing gain element and a Q-switch have respective end surfaces at substantially the Brewster angle, parallel to and facing each other, and separated by a narrow gap occupied by a transparent low-index-of-refraction material.

Abstract: A diode pumped solid-state laser is disclosed having: a block of a lasing gain material with at least two optical surfaces and a cavity means positioned around the block to define a laser cavity which includes a mode shaping means to form an eliptical resonator mode between the optical faces within the block; a high aspect ratio pumping laser diode light source is positioned outside one of said optical faces; and a means to image the pumping light beam from said source to substantially match the elliptical resonator mode.

Abstract: A diode imaging system using a single objective lens and a single cylindrical lens. This imaging system does not image perfectly point-to-point, and although not an apparent extension of imaging systems known in the prior art, it works advantageously for imaging beams from diode lasers having long narrow junctions used in pumping solid-state lasers.

Abstract: Apparatus and method for modulating the phase or the amplitude of a monochromatic light beam, the apparatus including in one embodiment a Mach-Zehnder interferometer that consists of two beam splitters or beam combiners, a fully reflective mirror and an electro-optical crystal for modulation of one of two beam components. The electro-optical crystal serves as an optical resonator for the portion of the light beam admitted into the crystal material, using total internal reflection of the light beam from two or more of the crystal surfaces. The crystal has a high finesse so that a relatively small change in voltage applied across the crystal produces a large (.apprxeq.180.degree.) change in the external phase shift associated with the modulated component of the light beam.

Abstract: In a laser, the laser gain member is optically pumped by a semiconductive source of pumping radiation having an elongated output beam aperture such as that provided by a single-wide stripe diode or diode array. The elongated beam of optical pumping radiation is twice reflected from a concave surface at non-normal angles of incidence and then focused onto the laser gain material for pumping same. The reflections serve to differentially focus rays diverging in the vertical plane from rays diverging in the horizontal plane to shape the pumping beam for improved pumping efficiency in the pumped mode volume of the laser gain material. In a preferred embodiment, a magnifying lens is disposed inbetween the source and the reflectors for decreasing the divergence of the pumping beam.

Abstract: An optical Faraday isolator includes a slab of Faraday rotator medium coated to define input and output faces and internal reflective surfaces for causing the beam to travel between the input and output faces along a zig-zag path. Permanent magnets polarized in a direction normal to the plane defined by the zig-zag beam path are disposed on opposite sides of the beam path. The magnets are paired on each side with serially alternating polarity and the like poles are in transverse registration on opposite sides of the beam path to produce an intense, unidirectional magnetic field parallel to the beam path within the rotator slab. A quarterwave plate introduces a compensating amount of elliptical polarization to cancel unwanted elliptical polarization effects of the slab and its coatings. A beam shaving aperture at the exit of the slab shaves off divergent backward travelling rays.

Abstract: An optical resonator, preferably of a solid state laser, is tuned by one or more sheets of piezo-electric material bonded to one or more tuning facets of an optically transparent solid state member portion of the resonator. A tuning voltage applied across the piezo-electric sheet tends to change the area of the bonded interface of the sheet to generate a set of tuning forces predominantly in the plane of the surface of the tuning facet. These tuning forces are transmitted through the tuning facet into the solid state portion of the optical resonator to produce a change in its refractive index and dimensional change which tunes the frequency of the optical resonator and the laser using same, if any. In a preferred embodiment, the piezo-electrically tuned optical resonator is an optically pumped ring resonator made of a lasant material such as Nd:YAG for tuning the output frequency of the ring laser.

Abstract: A diode pumped Nd:YAG laser is disclosed wherein the YAG laser rod is supported from the envelope of the pumping diode by means of telescoping glass tubes bonded together by means of u.v. curing adhesive. The diode pumped laser is supported from a heat sink via the intermediary of a pair of rotatable wedges for adjusting the tilt of the optical axis of the laser. A gradient refractive index lens focuses the pump radiation into the laser rod. The lens is adhered directly to the output window of the pump diode by means of refractive index matching adhesive.

Abstract: A seeded electro-optically Q-switches laser includes a pulser for pulsing the Q-switch within the seeded laser. The Q-switch pulser includes a pulse-shaping network having a saturable core inductor connected in series with the flow of current to the Q-switch for causing the developed pulse voltage waveform in Q-switch to have an initially reduced rate of change to reduce unwanted Fourier frequency components of the seed optical radiation in the optical resonator of the slave laser, whereby enhanced single-mode operation of the slave laser is obtained with reduced seed power.

Abstract: In a monolithic ring laser, the ring laser crystal is mounted in a monolithic heated support structure including a layer of solder which is readily softened by elevating the temperature of the heater to permit adjustment and readjustment of the optical alignment of the crystal. The monolithic crystal support includes a block of thermally insulative material interposed between the heating element and the surrounds for thermally isolating the heater and laser crystal from the surrounds.