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

Abstract: A crystalline material for use in a solid state tunable laser is YAG:Mn wherein the Mn is predominantly trivalent. The laser is tunable in the yellow-orange range (0.59-0.63 .mu.m) and the near infrared range (1.04-1.2 .mu.m).

Abstract: An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises Ytterbium doped apatite (Yb:Ca.sub.5 (PO.sub.4).sub.3 F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

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

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

Abstract: An optical source particularly suitable as a pump is provided. A gain medium such as a thulium doped fiber has an input end and an output end. The input end is optically coupled to a reflector to cause spontaneous emissions within a predetermined band exiting the input of the gain medium to be reflected back into the medium. Spontaneous emissions outside of the predetermined band are lost. An optical isolator can be provided to prevent the optical source from lasing, resulting in a moderate bandwidth optical pump. A cascaded embodiment is disclosed, in which the gain medium is followed by an optical amplifier for increased power.

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 solid-state tunable laser having a ND:YAG pumping source, a chromium-doped fosterite crystal lasing medium, a birefringent filter for selecting a specific fundamental wavelength, a pair of harmonic generating crystals mounted on counter-rotating platforms driven by stepper motors under the control of a computer, a partially reflective, partially transmissive mirror for directing the output of the pumping source through the lasing medium so that the lasing medium produces radiation having a range of fundamental wavelengths, and a fully reflective mirror for directing the radiation of the specific fundamental wavelength through the birefringent filter and the pair of crystals so as to produce radiation of a harmonic wavelength of the specific fundamental wavelength.

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: 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: 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 prism gain module is placed in a resonator for generating or amplifying coherent light energy. The module has a first and second side each with a planar surface. The surfaces are partially coated with a reflective material. The first and second sides are angled so that a resonator beam path is formed within the module such that coherent light energy enters an uncoated surface on the first side of the module of Brewster's angle, reflects off of the reflective material on the second and first sides, and then exits the module through the second side with an exit angle also equal to Brewster's angle. The prism gain module provides pump position flexibility by permitting coherent light energy to pump the gain module from multiple sides so long as the coherent light energy is focused along the beam path.

Abstract: A highly-efficient solid-state blue laser that exploits a strong emission line provided by a solid-state laser medium of neodymium-doped scandium oxide (Nd:Sc.sub.2 O.sub.3) to produce a beam of coherent blue light at a wavelength matching the absorption line of cesium at 455.6 nm (0.4556 microns). The solid-state blue laser includes the laser medium of neodymium-doped scandium oxide, a semiconductor diode laser array for optically pumping the laser medium to produce a beam of coherent infrared radiation at a wavelength of approximately 1367 nm (1.367 microns), and optical means for tripling the frequency of the beam of coherent infrared radiation to produce a beam of coherent blue light at the wavelength of approximately 455.6 nm. The solid-state blue laser is simple, highly efficient and provides relatively high power outputs.

Abstract: A laser system and method for producing a laser emission at a wavelength of substantially 2.8 microns and having a quantum efficiency of at least unity and a slope efficiency of about 36%. In a preferred embodiment of the invention, the laser system comprises a laser cavity defined by first and second reflective elements with one of the reflective elements operating as an output coupler; a crystal disposed in the laser cavity and having a GSGG host material doped with a preselected percent concentration of erbium, the GSGG host material and preselected percent concentration of erbium being selected so as to provide a quantum efficiency of at least unity by the .sup.4 I.sub.13/2 +.sup.4 I.sub.13/2 .fwdarw..sup.4 I.sub.9/2 +.sup.4 I.sub.15/2 upconversion process and a slope efficiency of about 36% when the crystal is resonantly pumped; and a resonant pump laser for directly pumping the .sup.4 I.sub.

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: A linear cavity laser system having a yttrium-aluminum-garnet laser rod for producing a fundamental wavelength of radiation having a front face and a longitudinal axis, a first mirror reflective of the fundamental wavelength but transmissive of a desired harmonic wavelength located in front of the laser rod along the longitudinal axis, a second mirror reflective of both the fundamental wavelength and the desired harmonic wavelength located to a rear of the lasing rod along the longitudinal axis, a phase matched crystal harmonic wavelength generator responsive to the fundamental wavelength for generating the desired harmonic wavelength of radiation arranged between the front mirror and the lasing rod along the longitudinal axis and a dichroic member transmissive of the fundamental wavelength but reflective of the harmonic wavelength arranged between the laser rod and the harmonic wavelength generator along the longitudinal axis.

Abstract: The invention relates to a solid laser with an emission wavelength lying between 0.5 and 0.65 .mu.m. A chromium-doped Mg.sub.2 SiO.sub.4 (forsterite) laser rod is pumped by a laser diode emitting between 0.75 and 0.8 .mu.m, this laser diode having an active layer which is Ga.sub.1-x Al.sub.x As based, with x lying between 0.1 and 0.18. The laser device finds particular application in the isotopic separation of uranium.

Abstract: Mixed silicates of yttrium and lanthanide and laser using monocrystals of these silicates. The laser has a laser cavity (2) containing as the light emitter a monocrystal (4), means (12,14) for amplifying the light from the monocrystal, means (14) for removing light from the laser cavity and optical pumping means (6), characterized in that the monocrystal is of formula (I):Y.sub.2-2x-2y M.sub.2x Yb.sub.2y SiO.sub.5 (I)in which M represents a lanthanide chosen from among erbium and thulium and x and y represent numbers such that 0<x.ltoreq.0.2 and 0<y.ltoreq.0.2.

Abstract: An up converting method and apparatus includes a crystalline structure responsive to light emitted from pump light for producing visible and/or ultraviolet light therefrom which is of a shorter wavelength than the pump light. This crystalline structure comprises a composition containing active ions of trivalent rare earth elements and a host material of either anhydrous rare earth halides or rare earth oxysulfides. This crystalline structure is represented by the atomic formula M.sub.(1-x) R.sub.x Z.sub.3 or M.sub.2(1-x) R.sub.2x O.sub.2 S where M comprises at least one rare earth element selected from the group comprising cerium, gadolinium, yttrium, lanthanum, and mixtures thereof, R is a dopant selected from the group comprising neodymium, thulium, erbium, holmium, samarium, and mixtures thereof, x is a value in the range from 0.005 to 1.0, and Z is a halogen selected from the group comprising chlorine, bromine, and iodine.

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

Abstract: A high concentration of diatomic molecules is caged in a host crystal by a crystal growth process, in which all other internal degrees of freedom of the diatomic molecule, except the vibrational, are frozen. Such a system provides an efficient mid-infrared, solid-state laser that can be pumped by a laser diode. Other uses include magnetic (Faraday) rotators, electro-optic switches, and Q-switches. The crystal growth process employs Czochralski-type or Bridgman-type processes under high pressure to introduce the diatomic molecule into the host lattice at a temperature slightly above the melting point of the host crystal, followed by slow cooling.

Abstract: Mixed strontium and lanthanide oxides and a laser using monocrystals of these oxides.These oxides with a magnetolead type crystalline structure have the following formula:Sr.sub.x Ln1.sub.y1 Ln2.sub.y2 Ln3.sub.y3 M.sub.z A.sub.a B.sub.b O.sub.19--kin which Ln1 represents at least one trivalent element selected from lanthane, gadolinium and yttrium; Ln2 represents at least one trivalent element selected from neodymium, praseodymium, erbium, holmium and thulium; Ln3 represents an element selected from bivalent europium or trivalent cerium with retention of electric neutrality by virtue of oxygen holes; M represents at least one bivalent metal selected from magnesium, manganese and zinc; A represents at least one trivalent metal selected from aluminum and gallium; B represents a trivalent transition metal selected from chromium and titanium; x, yl, y2, y3, z, a, b and k represent numbers so that 0<x<1, 0.ltoreq.y1<1, 0<y2<1, 0.ltoreq.y3<1, 0<z<1, 10.5<a<12, 0.ltoreq.b.ltoreq.0.

Abstract: A solid laser generator employing a flash light as light source for excitation and titanium-doped sapphire as laser medium, wherein cerium and/or erbium-doped quartz glass, transparent plastic or transparent ceramic, is disposed in the vicinity of the laser medium or in the vicinity of the flash lamp.

Abstract: The invention provides a laser medium having improved photodynamical properties. The medium includes the condensed phase, namely solid or liquid phase, of a mixture of one or more rare gases and a halogen donor. The gases are first combined and then condensed to form the laser medium. A solid state rare gas crystal laser is also provided.

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: In a solid-state laser device comprising, as a solid-state laser medium, a nonlinear optical crystal, such as Nd.sub.x Y.sub.1-x Al.sub.3 (BO.sub.3).sub.4, which generates a primary laser beam of a fundamental wavelength and which can convert the primary laser beam into a subsidiary laser beam of a harmonic wavelength, a pair of optical elements is brought into contact with both ends of the solid-state laser medium to form a resonator for the primary laser beam. The optical elements may be composed of optical thin films or reflectors attached to the ends of the medium. At least one of the ends of the medium has a spherical surface convex outwards of the medium so as to reflect the primary laser beam into the medium.

Abstract: Continuous laser action is sustained by a new pumping mechanism which relies exclusively on cooperative electronic transitions of coupled atoms or ions in solids. The present invention is the first of a new class of laser device which depends on energy-sharing interactions between colliding atoms in gases or active dopants in solid laser media to create the population inversion needed for amplification of light. In one specific embodiment, a laser crystal which is formed of calcium fluoride is doped heavily with trivalent erbium, and is provided with reflective coatings on respective first and second surfaces. A pumping energy is supplied whereby a pair of atoms are elevated to an initial excited state. Subsequently, one of the atoms loses energy so as to assume a ground state, the energy released thereby being made available to excite the second atom to a still higher quantum energy state.

Abstract: A solid state laser rod of an anisotropic material is more efficiently side pumped by using cylindrical lenses and a half-wave plate with linear laser diode arrays disposed along the length of the solid state laser rod such that the polarization of the diode array light is rotated to achieve a maximum absorption coefficient in the laser rod material. In addition, Fresnel reflection losses at the lens and laser rod surfaces are reduced by a 90.degree. polarization rotation.

Abstract: A method and apparatus for generating a high power beam of light is described in which individual laser pixel elements are laterally defined and isolated in a wafer of solid state gain medium material and mirrors are formed on each side of the wafer to produce an optical cavity resonator. An array of diode lasers is used to pump adjacent pixels to stimulate light emission by each pixel.

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: A process for reducing energy losses in crystals is disclosed which comprises:a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, andb. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal.Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light.

Abstract: A neodymium laser provides output at about 1.44 .mu.m, by selection of a neodymium doping level of between about 0.3 and 0.7N, preferably at 0.4N with reflectivity of the output mirror at about 90% for 1.44 .mu.m output. Selection of the reflectivity of the output mirror is adjusted to ensure that the excess of the gain over the absorption and transmission losses is maximized.

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%.

Abstract: A laser system and method for producing a laser emission at a wavelength of ubstantially 2.8 microns is disclosed. In a preferred embodiment of the invention, the laser system comprises a crystal having a host material doped with erbium; a laser cavity defined by first and second reflective elements at opposing ends of the crystal to form a reflective path therebetween; and resonant pumping means for directly pumping the .sup.4 I.sub.11/2 upper laser state of the erbium with a pump beam at a preselected wavelength to cause the erbium-doped crystal to produce a laser emission corresponding to the .sup.4 I.sub.11/2 .fwdarw..sup.4 I.sub.13/2 laser transition having a wavelength of substantially 2.8 microns, a portion of the laser emission at substantially 2.8 microns being outputted from one of the first and second reflective elements.

Abstract: A laser system is disclosed wherein neodymium laser is used to pump a holmium laser to produce a moderately high energy output pulse at about 3 microns. The holmium host has a concentration of holmium in execess of 15 percent and a praseodymium concentration of at least 0.005 percent.

Abstract: A microlaser is disclosed comprising: a gain medium having one face which is adapted be coupled to a source of optical pumping radiation and having an opposite face; harmonic conversion means having a close face which is located adjacent to and spaced apart from the opposite face of the gain medium and which is coated for high transmission at a fundamental and high reflectivity at a harmonic and having an opposite face which is coated for high transmission at the fundamental and some transmission at said harmonic; and polarization control means, located adjacent to and spaced apart from the opposite face of the harmonic conversion means, for controlling the polarization of the fundamental.

Abstract: A minilaser device exhibiting both laser and non-linear optical effects. The device includes a single laser crystal bar of NYAB which inhibits non-linear characteristics and serves as a self-frequency-doubling crystal having the laser and non-linear optical effects, and a pumping source for the device to generate laser light.

Abstract: Alignment of a birefringent device characterized by a first face and a second face cut at Brewster's angle so that a plane of polarization is defined. The optical device is secured in the optical path by a rotatable member having an axis of rotation that is normal to the Brewster faces of the optical device. Coupled with the rotatable member on the axis of rotation is a support allowing adjustment of the angular position about the axis of rotation of the rotatable member. An operator adjusts the angular position of the rotatable member until the C-axis lies in the plane of polarization. Even though the C-axis may not be parallel to the direction of polarization, the depolarization effects of the misalignment are eliminated by proper adjustment of the angular position relative to the plane of polarization. A tunable, solid state laser using the alignment apparatus with a birefringent filter achieves greater linear tuning range.

Abstract: A long wavelength NdYAG laser which is operable either in a surgical cutting mode where the wavelength of laser radiation is about 1.44 micrometers, or in a therapeutic coagulating mode where the wavelength of laser radiation is about 1.06 micrometers. The NdYAG laser combines the use of frequency selective laser mirrors together with a repetitively pulsed high peak current lamp to produce high laser power at both 1.44 micrometers and 1.06 micrometers. The NdYAG laser beam may also be coupled to and transmitted by a flexible fiber optic quartz cable so that both the coagulating 1.06 micrometer beam and the cutting 1.44 micrometer beam may be transmitted through the same fiberoptic cable.

Abstract: A laser system employing thulium and holmium in a trivalent state. The quantum levels of interest in the thulium and holmium are coupled so that one pumping photo absorbed by the thulium results in two photons emitted by the holmium, making for an unusually efficient laser system. The lower level is sufficiently depopulated at room temperature to allow laser operation without cryogenics. In preferred embodiments, the laser pump can be a laser diode, itself especially efficient, and whose output frequency is closely matched in photon energy to the thulium quantum state of interest, thus lending additional efficiency to the overall system. The thulium and the holmium exist in an yttrium-aluminum garnet crystal as lattice replacements for yttrium.

Abstract: In a laser-operated detecting device, the light source of a laser beam applied to a specimen under test is a tunable laser whose wavelength can be continuously tuned in a certain range. The detecting device is realized as a high speed liquid chromatography fluorescence detector, a high speed liquid chromatography Raman detector, a laser Raman spectroscopic measuring device, a coherent anti-Stokes Raman measuring device, or a microscopic Raman measuring device.

Abstract: Continuous laser action is sustained by a new pumping mechanism which relies exclusively on cooperative electronic transitions of coupled atoms or ions in solids. The laser depends on energy-sharing interactions between a trio of atoms in gases or active dopants in solid laser media to create the population inversion needed for amplification of light. In one specific embodiment, the laser crystal is formed of calcium fluoride doped heavily with trivalent erbium, and is provided with reflective coatings on respective first and second surfaces. A pumping energy is supplied whereby a three atoms are elevated to an initial excited state. Subsequently, two of the atoms lose energy so as to assume a ground state, the energy released thereby being made available to excite the third atom to a still higher quantum energy state. Thus, a cooperative energy interaction between the trio of atoms results in the double excitation of one of the atoms above the initial excitation state.

Abstract: A solid-state laser device includes a neodymium laser pump source capable outputting a pump beam of about 1.1 .mu.m wavelength, and a holmium laser being pumped by said 1.1 .mu.m pump beam to generate an output laser beam of about 3 .mu.m wavelength.

Abstract: A laser incorporating a laser medium disposed within a laser cavity and a pumping arrangement for selectively applying excitation energy to said laser medium. The laser medium contains upconverting material of the type which allows for the exchange of energy between electrons of the lasing ions at a given energy state below the meta-stable initial lasing state so that some of said exchanging electrons are upconverted to energy states at or above the meta-stable initial lasing state. The pumping arrangement applies energy of suitable wavelength and intensity for elevating electrons from energy levels below the given state to that state in sufficient numbers to support substantial upconversion and the resulting lasing.

Abstract: A commercial near resonant laser system with a trivalent rate earth ion doped solid state host, such as Nd:YAG, is pumped at an energy sufficient to excite the electrons from the ground level directly to the upper laser level. The laser system is then tuned to a transition from the upper laser level back to the ground level to produce high power output beams. Because the ground level will include a plurality of "Stark split levels", the necessary population inversions can be maintained and laser energy generated. However, the difference between the Stark split level from which the electrons are excited to the upper laser level, and the Stark split level to which the electrons decay in the light producing transition from the upper laser level, is slight. Thus, energy dissipated in heat as electrons decay in non-lasing transitions is minimized.

Abstract: A laser and method for producing a laser emission at a wavelength of substantially 2.8 microns is disclosed. In a preferred embodiment of the invention, the laser comprises laser diode means for emitting a pump beam at a preselected wavelength; a crystal; and a laser cavity defined by first and second reflective elements at opposing ends of the crystal to form a reflective path therebetween; the crystal having a preselected host material doped with a predetermined percent concentration of erbium activator ions sufficient to produce a laser emission at substantially 2.8 microns when the crystal is pumped by the laser diode means, a portion of the laser emission at substantially 2.8 microns being outputted from one of the first and second reflective elements at a slope efficiency of at least 5 percent, but preferably 10 percent, when the crystal is pumped by the pump beam.

Abstract: A full color upconversion laser pumped by a single wavelength infrared laser source is disclosed. The pump energy excites a rare earth doped crystal and can simultaneously lead to laser emission at several wavelengths. The laser includes a crystal of YLiF.sub.4 :Er 5% fabricated in a monolithic structure which incorporates the laser mirrors as dielectric coatings on spherical surfaces of the crysal rod; the mirrors are optically reflecting at one or more of the desired output wavelengths. The laser rod is mounted in a helium cryostat that permits the operating temperature to be varied between 15.degree. and 120.degree. K. The pump energy is supplied through one of the mirrors specifically designed to be simultaneously highly reflecting at the laser wavelength and highly transmitting at the pump wavelength. To achieve optimum efficiency a lens is used in the pump path to focus the pump beam in such a manner as to provide a match of the laser mode size and pumped region of the crystal.

Abstract: A room temperature solid state laser for producing a laser emission at a wavelength of substantially 1.96 microns is disclosed. In a preferred embodiment, the laser includes: a laser cavity defined by a plurality of coated reflective elements to form a reflective path thereamong; a laser crystal disposed in the laser cavity and capable of lasing at substantially 1.96 mircons and 2.01 microns when excited; and means for exciting the laser crystal to lase at substantially 1.96 microns and at substantially 2.01 microns. The laser crystal is comprised of a host crystal material capable of accepting Cr.sup.3+ and Tm.sup.3+ ions. Through their respective reflectivities at each of the wavelengths at substantially 1.96 microns and 2.01 microns, the coated reflective elements collectively operate to produce substantial loss in radiation at the wavelength of substantially 2.

Abstract: A room temperature, 1.5 .mu.m band laser is described. The lasant material in the preferred embodiment is Er:YAG with a 1% Er.sup.3+ doping. The pumping radiation is an intense 1.53 .mu.m beam produced by a laser diode. The solid-state lasant material produced 1.5 .mu.m band radiation with high efficiency.