Abstract: A diffusion reflector is formed of mica ceramics or fluorine plastics containing barium sulfate, on the surface of which gold or silver is vapor deposited to enhance a diffusion reflectance. A reflective cylinder is formed from said diffusion reflector, and laser rods and lamps are arranged in an internal space of the reflective cylinder to form a solid laser device. Thereby, light can be diffused without focussing light within the reflective cylinder, and the laser rods can be uniformly excited.

Abstract: High-power optical output (60) that exhibits a high degree of lateral and transverse spatial coherence from an unstable resonator semiconductor laser (14) is efficiently optically coupled into a lasant mode volume (76) of a solid-state laser (28). This apparatus and method of pumping enable the preferred lasants, Cr:LiCAF and Cr:LiSAF, to reach laser operation at a reduced pumping level.

Abstract: A discharge-excited laser apparatus includes a pair of discharge electrodes extending in a direction of an optical axis; a plurality of charging capacitors charged by a power source; a plurality of peaking capacitors arranged in parallel in a longitudinal direction of the discharge electrodes and receiving energy accumulated in the charging capacitors; and a plurality of semiconductor switches arranged with conductive plates in the longitudinal direction of the discharge electrodes and connected in series and in parallel to the peaking capacitors. The construction of the semiconductor switches enables uniform shift of the energy in the charging capacitors to the peaking capacitors and reduction of inductance of a loop for capacity shifting.

Abstract: An amplifier/filter combination including a fibre amplifier (4) and a fibre reflection/transmission filter (5) coupled to said amplifer. The fibre amplifier amplifies an input signal (1) in response to pump light (2) received from a laser. Preferably the fibre filter (5) is a chirped Bragg fibre filter which is arranged to filter out the unabsorbed portion of the pump light from the output amplified signal and which reflects the unabsorbed portion (7) of the pump light back to the amplifier (4) for re-absorption therein. The amplified signal (6) is transmitted by the filter (5) to a receiver.

Abstract: A flashlamp pumped laser is controlled to emit a series of narrow pulse width laser pulses in quick succession. A control circuit associated with the flashlamp receives firing signals of limited pulse duration and serves to ignite and extinguish the flashlamp in accordance with the leading and trailing edges of a single firing signal pulse. The laser generates a coherent light pulse corresponding to the pumping flashlamp pulse. The flashlamp control circuit includes a main capacitor which stores electric charge sufficient to provide current to the flashlamp for several pulses in succession. The circuit also includes a trigger capacitor which supplies current through a transformer coupled to the flashlamp to initiate current conduction therein.

Abstract: An internally folded scalable laser has a gain medium with an internal face nd an external face and at least one internal-fold face subtending an angle which may be about 90.degree.. An output coupler that is partially reflective of the resonator mode is oriented to receive and reflect resonator mode in a direction normal to the internal face to avoid resonator mode astigmatism and to define a folded hemispherically-shaped resonator cavity extending from the output coupler and through an active volume in the gain medium to the external face. A pumping mode source disposed adjacent to the external face is oriented to focus a first pumping mode in a direction normal to the external face in a boom waist at or inside the external face in the folded resonator cavity to define an active volume in the gain medium and to avoid pumping mode astigmatism.

Abstract: A laser having a Cr.sup.3+ doped Colquiriite mineral host gain element, such as Cr:LiCAF, Cr:LiSAF or Cr:LiSGAF, is pumped by the pumping beam from at least one visible laser diode to provide tunable laser emission. TheSTATEMENT OF GOVERNMENT INTERESTThe invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

Abstract: A high-power continuous-wave laser resonator (10) is provided, wherein first, second, third, fourth, fifth and sixth mirrors (11-16) form a double-Z optical cavity. A first Ti:Sapphire rod (17) is disposed between the second and third mirrors (12,13) and at the mid-point of the length of the optical cavity, and a second Ti:Sapphire rod (18) is disposed between the fourth and fifth mirrors (14,15) at a quarter-length point in the optical cavity. Each Ti:Sapphire rod (17,18) is pumped by two counter-propagating pump beams from a pair of argon-ion lasers (21-22, 23-24). For narrow band operation, a 3-plate birefringent filter (36) and an etalon (37) are disposed in the optical cavity so that the spectral output of the laser consists of 5 adjacent cavity modes. For increased power, seventy and eighth mirrors (101, 192) are disposed between the first and second mirrors (11, 12) to form a triple-Z optical cavity.

Abstract: The object of the invention is a radio frequency gain follower, in particular for free electron lasers, wherein the equivalent of a variation of the length of the optical cavity is achieved by means of a variation of the time frequency of the packets of electrons that are supplied to the laser by an accelerator machine, in particular a microtron, characterized in that said microtron is driven, through a one or more stage amplifier section, by a frequency generator in turn driven by a function generator.

Abstract: An apparatus for preionization of gas in a pulsed gas laser by means of soft X-ray radiation comprises an elongated cathode (26) which is heated by thermal radiation or electron bombardment and which is arranged parallel to a likewise elongated anode (18) in an evacuated housing.

Abstract: An optical amplifier using either rare-earth doped optical fiber, which can amplify an optical signal when a pumping light is injected, or a laser diode amplifier, which can amplify an optical signal by injection of an electric current. The amplifiers being of simple construction and having a gain which can be maintained constant through feedback control based on the detection of spontaneous emission from the sides of either the rare-earth doped optical fiber or the laser diode. The control being performed without the need for detection of input or output optical signal of the optical amplifier.

Abstract: An upconversion system and method for producing red, green and/or blue emissions in response to an infrared pump is operable at room temperatures. Implemented either as a laser or as phosphors, the host medium has a hexagonal CsNiCl.sub.3 -type crystal structure, a phonon wave number less than 200 cm.sup.31 1, and a rare earth dopant occupying paired lattice vacancies. The host medium has the formulation AMX.sub.3, where A is a monovalent metal, M is a divalent metal and X is a halogen; the system has been demonstrated with CsCdBr.sub.3 :Er. Green, blue and red emissions are stimulated with infrared pumps of about 800 nm, 980 nm and simultaneous 800/980 nm, respectively.

Abstract: An elongated cylindrical pump lamp which coaxially surrounds a lasing material and provides high energy excitation thereof uniformly around and along the length of the lasing material. The pump lamp chamber has a length to diameter ratio of approximately one to one to four to one wherein the low pressure contents (such as xenon) is excited by an electric field and produces a uniform flash discharge along the length of the pump lamp and radially about the lasing material to efficiently excite the lasing material. Optical pumping efficiency is increased with integral mirror surfaces and circuitous internal cavities providing elongated internal discharge paths. Alternate embodiments include a laser pump lamp wherein the outer surface of the lasing material forms the interior wall of the pump lamp chamber.

Abstract: Arrays of extended crystalline and non-crystalline structures are created using light beams coupled to microscopic polarizable matter. Polarizable matter adopts the pattern of an applied, patterned light intensity distribution. Further, polarizable matter itself scatters applied light, resulting in production of a stable, bound configuration of that matter. Alternatively, polarizable matter can simultaneously adopt the pattern of an applied patterned light intensity while the incident light scattered by the matter itself acts further to organize the matter. Dielectric, semiconductor, metal, molecular, atomic and biological matter can be organized using light to fabricate numerous devices including mechanical and optical filters, self-organizing Bragg lasers, templates for epitaxy, photonic semiconductors, optical components including holograms and diffractive optical elements as well as two dimensional membranes of living biological cells.

Abstract: The invention relates to a high energy solid-state laser using a new optical pumping device, comprising optical fibers coupled to optical pumping sources of great power and to a laseing medium. The coupling surface through which optical pump energy is transmitted onto the laseing medium is displaced by motor for improved heat dissipation and selective coupling of the pump energy to various resonant cavities.

Abstract: Power output and power conversion efficiency of an intracavity non-linear optical laser is substantially increased by reducing the effect of thermal focussing per unit of pump energy enabling a stable resonator cavity at high input powers by utilizing a closely coupled reflector, multi-gain media configuration, and various pump source filters and/or semiconductor laser diode pumping.

Abstract: A solid-state laser and method of operating the laser is described having a microwave driven (MWD) visible excimer fluorescence source for exciting a solid-state laser. The laser of this invention provides an efficient, compact, and tunable solid-state laser preferably for use with tunable vibronic laser crystals.

Abstract: A system for producing ultra-high peak power pulses employs a plurality of solid state amplifying materials, such as Nd:glass, alexandrite, and Ti:sapphire, to achieve stretching of a pulse prior to amplification by a factor of approximately between 100 and 10,000. The time-stretched pulse is amplified by many orders of magnitude, illustratively 10.sup.9. After time-stretching and amplification, the pulse is then recompressed to its original duration. Pumping of the multiple solid-state elements is performed simultaneously using an alexandrite laser which is tunable between approximately 700 and 800 nm. The pumping energy has a pulse duration which is less than the fluorescence lifetime of the excited solid-state media.

Abstract: A solid state lasing medium is pumped to produce a high repetition rate laser beam. The laser medium is pumped to cause maximum population inversion. The laser medium is greater in diameter than the aperture that defines the allowable beam path. In the preferred embodiment the off-axis laser beam that is produced is steered to become an on-axis laser beam using a novel SBSA (spinning beam steering assembly). The output of the laser is increased because as the SBSA spins, the area of the lasing medium that is not lasing is being charged or pumped. The laser medium can also be hollow to allow for pumping from either outside or inside the hollow bore or both. Similarly, this hollow bore in the laser medium could also allow cooling fluids to be circulated therethrough. Different embodiments of the SBSA are disclosed, including a variety of methods to pump the laser medium. Also, disclosed is a novel field removable or replaceable laser medium housing assembly.

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: Atoms in a neodymium:glass rod 20 are excited to a substantially spatially uniform metastable state by flashlamps 21. A flowing fluid 26 cools the flashlamps, but not the rod; so that low temperature gradients are maintained in the rod during isothermal laser operation. Automatic control means 22 turn off the electrical power supply 24 when the temperature in the rod reaches a predetermined limit. A flowing fluid 23 then cools the rod, at a rate low enough to avoid thermal stress therein, while it is not lasing. Segments of reflectors 25 focus the pump photons in the rod so as to substantially balance the cylindrical lensing action of the rod against the radial attenuation through it, and thus to provide substantially uniform density of stored energy in the rod.

Abstract: A solid-state laser oscillator has a semiconductor laser for biasing a solid-state laser to a threshold value or more and a semiconductor laser for pulse-pumping the solid-state laser. A pulse pump light having a pulse width which is equal to a cycle of relaxation oscillation or more is fed to the solid-state laser through the semiconductor laser for pulse pump thereby to suppress remarkably a relaxation oscillation.

Abstract: This invention relates means for illumination of sealed bulbs containing an predetermined inner gaseous environment to be excited to a spontaineous emission predominately by frequency modulated photon pumped into sealed bulb through a fiber-optic waveguide by a laser, said waveguide being clad where is extends from laser and is coupled to sealed bulb and unclad where it extends through sealed bulb, and further has an intragally formed reflective end section for provisions of feedback of frequency modulated photons through the waveguide core at the output end, thereby producing counter-travelling photons within the waveguide causing said photons to collide at a variety of incident angles as to cause photons to be emitted from the unclad waveguide within sealed bulb therefore stimulating the inner gaseous environment to a spontaineous emission which in turn stimulates a frequency modulated fluorescent photon interaction coating source which creates visible light.

Abstract: An end pumped solid-state laser is comprised of a resonator formed of a pair of mirrors and a laser rod disposed between the pair of mirrors, an exciting light source for generating a pumping light which excites the laser rod and a converging optical element for converging the pumping light from the exciting light source so that the converged pumping light is irradiated on an end face of the laser rod. The wavelength of the light generated from the exciting light source is widened in band and/or a converging optical element having a large wavelength dispersion is employed, whereby heat generation in the optical axis direction of the laser rod is uniformed so as to generate a laser beam of large power.

Abstract: The 1.06.mu. Nd transition in a co-doped Cr,Nd:Gd.sub.3 Sc.sub.2 Ga.sub.3 sub.12 (Cr,Nd:GSGG) gain element is obtained by diode pumping Cr.sup.3+ at 670 nm and produces efficient, low threshold laser operation. Although co-doped Cr,Nd:GSGG was developed for more efficient flashlamp pumping, it has the desirable property of having an extraordinarily broad absorption to allow for efficient diode pumping relative to the Nd:YAG laser. The consequent broad bandwidth tolerance of the Cr,Nd:GSGG for the diode pumping radiation allows diode pumping of the 1.06.mu. transition without regard to the wavelength of the visible diodes which has the potential for reducing the cost of the semiconductor pump and also demonstrates the extended versatility of these diodes which previously had been restricted to pump the Cr.sup.3+ tunable vibronic lasers. CW and long pulse diode pumping provided pump power levels as high as 300 mW cw and 1 W pulsed. The lowest threshold power was measured at 938 .mu.

Abstract: There is disclosed a new superfluorescent source comprising a long fiber doped with a lasing material presenting three-level transitions, such as Erbium. Due to the ground state signal absorption present in three-level systems, the source of the present invention can achieve backward signal quantum efficiencies well in excess of the limit of 0.5 exhibited by four-level systems. The source can be used in a Sagnac interferometer which may comprise an optical isolator because of possible high feedback.

Abstract: A laser apparatus and method is disclosed comprising a first lasant material which is located in an optical cavity and which produces laser radiation of a first wavelength, and a second lasant material which is pumped by radiation from the first lasant material, which absorbs laser radiation at the first wavelength in an amount generally comparable to the Optimum Output Coupling, which functions as the output coupler for the optical cavity and which lases at a second wavelength. The first lasant material and the second lasant material are preferably selected to have minimal losses such that there is a net gain in the cavity.

Abstract: In a laser amplifier a high efficiency pumping scheme mode matches the TEMOO laser mode volume with a plurality of linearly spaced laser diode pumping sources positioned along a lateral side of a block of laser material. The optical path within the block is configured in a tightly folded zig-zag configuration. Pump radiation from the diode pumping sources is collimated by an optical fiber end the fold angle is selected to mode match the pump radiation to the mode volume.A laser oscillator is followed by one or more cascaded amplifier stages including a block of laser material arranged in a tightly folded zig-zag configuration. Pump radiation from the diode pumping sources is collimated by an optical fiber and the fold angle is selected to mode match the pump radiation to the mode volume.

Abstract: An optical wavelength conversion method employs a bulk-crystal-type optical wavelength converter device of a single crystal of nonlinear optical material known as PRA. Linearly polarized fundamental waves whose wavelengths range from 450 to 4,000 nm are applied to the bulk single crystal, and angle phase matching of the type I is achieved, thereby producing a wave whose frequency is the sum of the frequencies of the applied fundamental waves. A laser-diode-pumped solid-state laser includes a solid-state laser rod doped with a rare-earth material such as neodymium or the like and pumped by a semiconductor laser, and a bulk single crystal of organic nonlinear optical material disposed in a resonator. The bulk single crystal converts the wavelength of a laser beam which is oscillated by the solid-state laser rod and the wavelength of a pumping laser beam into the wavelength of a wave whose frequency is the sum of the frequencies of the laser beams.

Abstract: A printing device employs a semiconductor laser source for producing a laser beam, and a semiconductor-laser-pumped solid-state laser. The solid-state laser includes an optical resonator, such as a nonlinear optical element for effecting wavelength conversion, and a solid-state laser material disposed therein. The solid-state laser material is optically pumped by the laser beam from the semiconductor laser source and produces a laser beam to be applied onto a photosensitive sheet of paper. Responsive to print data, the intensity of the laser beam from the semiconductor laser source is varied between a first intensity level and a second intensity level. The photosensitive sheet of paper is insensitive to the laser beam when the laser beam from the semiconductor laser source is at the first intensity level, whereas it is sensitive to the laser beam when the laser beam from the semiconductor laser source is at the second intensity level.

Abstract: A laser is disclosed comprising: a source of optical pumping radiation; a lasant rod; an input mirror; two quarter-wave plates; polarizing means, adjacent to a quarter-wave plate, for polarizing said lasant light radiated from said rod; second harmonic generating means for producing an output at twice the frequency at which said rod lases; and an output coupler.

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: An electronics controller for controlling the power supply of a laser operating in a pulse mode is disclosed. The power supply is of the type having resonant DC converter, charging a capacitive storage means with an inverter stage driving the laser discharge tube. The current supplied to the laser discharge tube is monitored. In addition, the voltage of the capacitive storage means is also measured. Set points for the current, the voltage, and on/off are provided to the electronics controller as the comparison points for the controller. Based upon the voltage and current detected, and the set points provided, the controller controls the on/off of the converter and its frequency, and the on/off of the inverter.

Abstract: Disclosed is a method for generaing coherent optical radiation by intracavity optical mixing in a cavity that is resonant for the radiation generated by the lasing of a lasant material and an input radiation.

Abstract: A pumping light source drive system is disclosed for driving pumping light sources of an optical amplifier which is composed of a rare earth doped optical fiber doped with a rare earth element and said pumping light sources. The pumping light sources are always held in operation. The output signal power at the output of the rare earth doped optical fiber or the combined power of the pumping light sources is detected and compared with a predetermined reference power to control the output power of the pumping light sources, so that the output signal power or the combined power of the pumping light sources reaches a predetermined value.

Abstract: A wavelength stabilization apparatus and method for a superfluorescent source comprising a SFS (superfluorescent source) comprising a fiber with a core doped with lzaing 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 th esample 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: An optical device for illuminating an object with a rectangular pattern having a uniform light intensity distribution includes n (n.gtoreq.1) polarization separating elements which a laser beam emitted from a laser source enters and each of which separates the laser beam into two beams in two directions. The angle of separation by the polarization separating element is set to be 2.sup.(n-1) times of the smallest one of the separation angles of the polarization separating elements used. At least one quarter-wave or half-wave plate is combined with the polarization separating elements. An imaging lens is provided for forming 2.sup.n beam spots on the object such as an optical laser disk plate.

Abstract: A method and device for preventing premature optics burn-out in a laser having a solid gain medium is provided. The invention involves preheating the gain medium by supplying power at a level which is sufficient to set up a thermal lens, yet insufficient to cause substantial production of laser light. In one approach, a simmer routine is overlaid on a ramp routine, so that the power supplied to the gain medium is gradually increased during the warm-up period.

Abstract: An external cavity semiconductor laser system is disclosed wherein multiple segments of semiconductor material are excited with an array of pump sources. In one embodiment, a laser beam is reflected in a pattern to pass through multiple excited segments on a wafer of semiconductor material. In another embodiment, a series of wafers disposed in a laser cavity are excited. This pumping system spreads out the thermal load while providing a high power, high quality, laser beam.

Abstract: A chrysoberyl solid state laser comprising:(a) a rod-like laser medium composed of a chrysoberyl single crystal containing trivalent titanium ions as luminescent ions, the direction of c-axis of said crystal being made approximately the same as the longitudinal direction of the rod.(b) a means for generating excitation light for exciting said luminescent ions to emit light therefrom.(c) a means for focussing excitation light, generated by said means for generating excitation light, in said laser medium, and(d) a light resonator for generating oscillated laser light by resonating the light emitted from said luminescent ions with said focussed excitation light.

Abstract: A CO.sub.2 slab waveguide laser (10) is disclosed including a pair of spaced apart electrodes (36,38) having opposed light reflecting surfaces. The electrodes are dimensioned in a manner to guide light in a plane perpendicular to the reflecting surfaces. Light parallel to the reflecting surfaces is not constrained other than by the resonator mirrors (30,32). The resonator structure includes a negative branch unstable resonator in the nonwaveguide dimension. A stable resonator is used in the waveguide dimension but the mirror spacing from the end of the guide is based in part on the configuration of the unstable resonator. A unique support structure is disclosed for maintaining the electrodes in a spaced apart orientation without confining the discharge. Further refinements are disclosed for cooling the laser and for accommodating thermal expansion of the parts. An improved adjustable mirror assembly (26, 28) is provided which allows the tilt angle of the mirror to be varied from outside of the housing.

Abstract: A laser-diode-pumped solid-state laser including a solid-state laser rod doped with a rare-earth material such as neodymium, a semiconductor laser for emitting a laser beam to pump said solid-state laser rod to oscillate a beam, and a resonator including a bulk single crystal of organic nonlinear optical material for converting the wavelength of the beam which is oscillated by said solid-state laser rod. The organic nonlinear optical material is preferably PRA, MNA, NPP, NPAN, MAP, m-NA, or the like. The semiconductor laser may comprise a single-transverse-mode, or a single-longitudinal-mode semiconductor laser.

Abstract: Solid state and dye lasers are described which are tunable over a wide spectral region, are operable at high repetition rate, are uniformly narrow in spectral width over the tuning range, and produce a spatially uniform, single longitudinal mode beam. In one embodiment having a simple grazing-incidence cavity, the laser comprises: (a) a longitudinal pump beam with a KiloHertz (KHz) repetition rate; (b) a resonating cavity comprising a first fixed mirror, a diffraction grating, and a second rotatable mirror; and (c) an active solid state or dye medium within the cavity. In this embodiment, (i) the pump beam is passed through the fixed mirror and directed at the active medium; (ii) the emission from the active medium strikes the grating near a grazing angle; (iii) the rotatable mirror is placed at a first order diffraction position from the grating and reflects the desired wavelength radiation back into the cavity; and (iv) the output is derived from the grating at the zeroeth diffraction order.

Abstract: Apparatus for controlled ablation of material from a predetermined working point, comprising a first laser, in particular excimer laser, for generating laser radiation pulses having a wavelength in a wavelength range suitable for the ablation, in particular in the ultraviolet spectral range, further comprising a radiation analyzer such as a spectrometer for analysis of material-specific radiation from the ablation plume forming at the working point, and a second laser, in particular a tunable dye laser, for generating a further laser radiation in a wavelength range which is different from said first wavelength range and which is better suited for the resonant stimulation of the radiation serving for the analysis than the ablation radiation wavelength range.

Abstract: Disclosed is a laser source with beam scanning, of the type comprising: a pump laser source emitting a pump beam with a determined wavelength; a pressurized gas cell receiving the pump beam and emitting, by Raman effect, an output beam with a wavelength called a Stokes wavelength; a control light source transmitting a control beam to the gas cell, this control beam having a wavelength that is substantially equal to the Stokes wavelength; wherein said light source includes means for the spatial and/or temperal modification of the injection of the control photons of the control beam into said cell constituted by a multiple-laser strip structure, forming a power slave laser and cooperating with means for modifying the radiation pattern of said multiple-laser strip structure, so as to prompt the emission of the output beam in a variable direction.

Abstract: An all-solid-state laser system is disclosed wherein the laser is pumped in the longwave wing of the pump absorption band. By utilizing a laser material that will accept unusually high dopant concentrations without deleterious effects on the crystal lattice one is able to compensate for the decreased cross section in the wing of the absorption band, and the number of pump sources which can be used with such a material increases correspondingly. In a particular embodiment a chromium doped colquiriite-structure crystal such as Cr:LiSrAlF.sub.6 is the laser material. The invention avoids the problems associated with using AlGaInP diodes by doping the Cr:LiSrAlF.sub.6 heavily to enable efficient pumping in the longwave wing of the absorption band with more practical AlGaAs diodes.

Abstract: Co-ionization of the gas in the optical cavity of a laser, the laser employing only two electrodes, is accomplished by employing a low energy source to commute a non-switched higher energy source. The low energy source will generate a discharge in the laser medium thereby causing power to be deposited from the higher energy source into the laser medium.

Abstract: A low threshold resonator for an alexandrite laser receives a 680 nm pumping beam from at least one laser pump to provide alexandrite laser emission at around 751 nm. An alexandrite crystal or rod receives the 680 nm beam and has an exterior face provided with a dichroic coating highly transmissive to the 680 nm beam and highly reflective to the 751 nm emission and has an interior face provided with an AR coating antireflective to the 751 nm emission. A mirror, provided with a HR coating that is highly reflective to the 751 nm emission, has an appropriate radius of curvature and is appropriately spaced from the exterior face of the alexandrite rod to focus reflected 751 nm emission in a resonator mode on the exterior face of the alexandrite rod to assure low threshold pumping thereof. The mirror has a radius of curvature which is the same as the spacing between the exterior face of the alexandrite rod and the mirror to focus the reflected emission in the resonator mode in a spot size on the exterior face.

Abstract: An optical amplifier having one or more amplifier regions with a noncollinear light path provided by curved or folded waveguides therein between input, output and reflective surfaces provided, for example, by a low reflectivity front facet and a high reflectivity rear facet. The amplifier regions are electrically pumped via conductive contacts which may be individually addressable for each amplifier region to provide phase control of the array of emitted light. Light is accepted through the front facet by a first amplifier region, is reflected from the rear facet and is emitted through the front facet. If there are multiple amplifier regions, a portion of the light is reflected by the front facet into an adjacent amplifier region. The light path is incident on the front and rear facets at an angle other than normal thereto and preferably at most 10.degree. from normal.

Abstract: A room temperature solid state laser for producing a laser emission at a wavelength of substantially 2.09 microns is disclosed. In a preferred embodiment, the laser includes: a laser cavity defined by first and second reflective elements opposing each other on a common axis to form a path therebetween; a laser crystal disposed in the laser cavity, the laser crystal having a host material capable of accepting Cr.sup.3+ sensitizer ions, Tm.sup.3+ sensitizer ions and Ho.sup.3+ activator ions; an amount of Cr.sup.3+ sensitizer ions between about 0.3% and about 2% dispersed within the host material; an amount of Tm.sup.3+ sensitzer ions between about 3% and about 12% dispersed within the host material; and an amount of Ho.sup.3+ activator ions between about 0.1% and about 0.7% dispersed within the host material; and flashlamp and means for exciting the laser crystal to produce a laser emission at substantially 2.09 microns with a slope efficiency of at least 4%, and preferably of at least 5%.