Abstract: A laser-medium in the form of a dielectric crystal or glass doped with tetravalent chromium. The dielectric crystals are of olivine-like structure such as germanates of formula (A) (RE)GeO.sub.4 where (A=Na or Li, RE=Y, Lu or Gd), crystals of willemite structure Zn.sub.2 (Si or Ge)O.sub.4 tetrahedral sites, or any other single-crystal or polycrystalline compound containing the (Si.Ge)O.sub.4 tetrahedra in its crystal lattice, such as Ca.sub.3 La.sub.2 (SiO.sub.4).sub.6 and crystals such as YAG (Y.sub.3 Al.sub.5 O.sub.12).

Abstract: A Ho:YLF crystal including Tm as sensitizers for the activator Ho, is optically pumped with a semiconductor diode laser array to generate 2.1 .mu.m radiation with a pump power to output power of efficiency as high as 68%. The prior-art dual sensitizer system of Er and Tm requires cooling, such as by LN.sub.2, but by using Tm alone and decreasing the concentrations of Tm and Ho, and decreasing the length of the laser rod to about 1 cm, it has been demonstrated that laser operation can be obtained from a temperature of 77.degree. K. with an efficiency as high as 68% up to ambient room temperature with an efficiency at that temperature as high as 9%.

Abstract: A room-temperature, solid state laser for producing a CW laser emission cinuously tunable over the approximate spectral range of 1.86 to 2.14 microns is disclosed. In a preferred embodiment, the laser comprises: a diode pump laser for producing a CW pump beam at a preselected wavelength; a laser cavity defined by first and second reflective elements opposing each other on a common axis to form a reflective path therebetween; a laser crystal disposed in the laser cavity, the laser crystal having a host material doped with a concentration of thulium activator ions sufficient to produce a CW laser emission in the range of a plurality of wavelengths determined by the Stark components in the .sup.3 F.sub.4 to .sup.3 H.sub.

Abstract: A room temperature solid state laser for producing a laser emission at a wavelength of substantially 2 microns is disclosed. In a preferred embodiment, the laser comprises: a laser crystal having a host crystal material doped with an effective percent concentration of CR.sup.3+ sensitizer ions and with an effective percent concentraton of Tm.sup.3+ activator ions; and a flashpump for exciting the laser crystal to produce a laser emission at substantially 2 microns at a slope efficiency of at least 2 percent.

Abstract: A room temperature laser system for producing a CW laser emission at substially 2.3 microns is disclosed. In a preferred embodiment, the laser system comprises a laser diode source for producing a CW pump beam at a preselected wavelength; and a fiber laser doped with thulium activator ions sufficient to produce an output CW laser emission at a wavelength in the range of 2.2-2.5 microns when the fiber laser is pumped by the CW pump beam.

Abstract: A room-temperature, laser-pumped, Q-switched, thulium-doped, solid state laser for producing pulses of laser emission at substantially 2 microns is disclosed. In a preferred embodiment, the laser comprises: a laser cavity defined by first and second reflective elements opposing each other on a common axis to form a reflective path therebetween; a laser crystal disposed in the laser cavity, the laser crystal having a host material doped with an amount of thulium activator ions sufficient to produce a laser emission at substantially 2 microns from the .sup.3 F.sub.4 to .sup.3 H.sub.

Abstract: Mixed lanthanide-magnesium aluminates and lasers using monocrystals of these aluminates. These lasers in particular incorporate two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbito-aluminate emitting visible or infrared light, amplified between a mirror, a polarizing prism being used for passing to the outside of the laser the amplified light beam. The aluminate is of formula: (La.sub.1-x Tr.sub.x).sub.1-y-v Mg.sub.1-z-t Al.sub.11-u+y+2Z/3 Cr.sub.u O.sub.19-t-3v/3 in which Tr represents (a) at least one single trivalent substance chosen from among lanthanides, Y.sup.3+, Sc.sup.3+, or (b) at least one pair of lanthanides formed from a divalent element and a trivalent element, while retaining the electrical neutrality by adding aluminum or oxygen deficiencies, or any combination of (a) and (b); x is a number such that 0.ltoreq.x<1; y and v are numbers such that 0.ltoreq.y+v.ltoreq.0.4; z and t are numbers such that 0.ltoreq.z+t<1, provided that when z=t=O, y+v is .noteq.

Abstract: An erbium-doped fiber laser amplifier (1), characterized by the fact that said fiber (3) is doped to a concentration lying in the range 5 ppm to 50 ppm, that the length of said fiber lies in the range 250 m to 30 m depending on the selected concentration of doping, and that the radial position of the doped zone substantially coincides with the energy maximum of the set of propagation modes in said fiber at the pumping wavelength.

Abstract: Doped lanthanum orthogallate laser materials produced in the form of large perovskite-type doped single crystals are disclosed. Doped single crystals of lanthanum orthogallate are grown from a pure melt of lanthanum oxide, gallium oxide and dopant oxide while controlling the major crystallographic direction of solidification. Dopants are selected from the rare earth series elements, first transition series elements and actinide series elements.

Abstract: A gain medium is disposed between two mirrors to form a resonant cavity. The cavity length is selected so that the gain bandwidth of the gain medium is less than or substantially equal to the frequency separation of the cavity modes and such that a cavity mode frequency falls within the gain bandwidth. A nonlinear optical material is disposed either inside or outside the cavity to generate new laser wavelengths. The nonlinear optical material may be contained in a cavity which is resonant at the microchip laser frequency. Alternatively, the microchip laser may be tuned, for example thermally or by the application of a longitudinal or transverse stress, to the frequency of the resonant cavity. The laser is optically pumped by any appropriate source such as a semiconductor injection laser or laser array. Suitable gain media include Nd:YAG, Nd:GSGG and Nd pentaphosphate, and suitable non-linear optical material include MgO:LiNbO.sub.3 and KTP.

Abstract: A diamond laser formed of a synthetic diamond provides a high output power and a variable wavelength in the near infrared region. The maximum value of the optical density of H2 centers in the direction of the pumping light is in the range of 0.01 to 4. Laser action is caused in the range of 1000 to 1400 nm by an external pumping light at 650 to 950 nm. Such a diamond laser is produced by preparing a synthetic Ib type diamond having a nitrogen concentration within the range of 1.times.10.sup.17 to 8.5 10.sup.19 atoms/cm.sup.3, subjecting this synthetic diamond to an electron irradiation with a dose of not less than 5.times.10.sup.17 electrons/cm.sup.2, and heat-treating the synthetic diamond in a vacuum of not more than 1 Torr or in an inert gas atmosphere and at a temperature within the range of 1400.degree. to 1850.degree. C.

Abstract: A blue-green laser (450-550 nm) uses a host crystal doped with Tm.sup.3+. The Tm.sup.+ is excited through upconversion by a red pumping laser and an IR pumping laser to a state which transitions to a relatively lower energy level through emissions in the blue-green band, e.g., 450.20 nm at 75 K. The exciting laser may be tunable dye lasers or may be solid-state semiconductor laser, e.g., GaAlAs and InGaAlP.

Abstract: A solid state laser including a block of Nd:YVO.sub.2, Nd:YSAG, or Nd:YAB laser material having a cavity-defining mirror at one of its end surfaces is pumped by a laser diode pumping source having narrow bandwidth and is caused to lase in a single longitudinal mode by controlling the relationship between the pump power, the bandwidth of the lasing transition within the laser material, and the absorption depth of the pump radiation within the laser material.

Abstract: Mixed lanthanide-magnesium gallates and laser using monocrystals of these gallates. This laser has two flash lamps for longitudinally pumping a monocrystalline rod of a magnetoplumbite-type gallate emitting a light ranging from the UV to the IR, which is amplified between two mirrors and a polarizing prism serving to pass to the outside of the laser the amplified light beam. The gallate is of formula: ##STR1## in which M.sup.1 represents Nd, Pr, Ce, Nd-Ce or Pr-Ce in the trivalent state; M.sup.2 represents aluminium, optionally partly substituted by scandium and/or indium; k is a number between 0.94 and 1; x is a number between 0 and 1; t is a number such that 0.ltoreq.t.ltoreq.0.05, provided that t is.noteq.0 when x=0 and that x is .noteq.0 when t=0; v is a number such that 0.ltoreq.v+t<1 and z is a number between 0 and 0.5.

Abstract: A laser system in which the laser medium is a single crystal of Cr.sub.3+ :Mg.sub.2 SiO.sub.4 is disclosed. In one embodiment, the system comprises a single crystal of chromium doped forsterite and a cavity which includes a pair of 30 cm. radius mirror having high transmission at 543 nm (the pump wavelength) and high reflectivity in the 1150-1350 nm range. Room temperature vibronic pulsed laser action is obtained with this cavity. Laser action has been observed at 1235 nm and a bandwidth of 25 nm. The wavelength range is suitable for transmission through optical fibers and is useful in laser ranging and remote sensing. Because of the ultrawide fluorescence bandwidth and a 15 fluoroescence lifetime the system is suitable for high intensity, tunable, cw, Q switched mode locked operation. In the mode locked operation pulses as short as 10-500 femtosecond may be generated. A number of different embodiments of the invention are described.

Abstract: A multiple crystal, single pumping cavity laser system comprises an optical pumping cavity, several laser crystal rods disposed in the cavity and having differently sized diameters and with their axes parallel, an optical coupling device for coupling the rods in a chain of increasing diametrical size, an optical pumping source for providing an optimum pumping level for the largest rod, and attenuators for all but the largest sized rod for attenuating the energy absorbed by the smaller rods. Since all of the laser rods are disposed and pumped in a single pumping capacity, only a single pumping source is required. The housing containing the pumping cavity is thermally and mechanically isolated from the rail holding the other system components to prevent shock from being transmitted to the other components.

Abstract: In a laser apparatus which includes a laser medium exhibiting thermally induced optical distortions, and flash lamp mounted near the laser medium to provide laser pumping radiation, an absorbing filter is mounted between the flash lamp and the laser medium for absorbing radiation in the output spectrum of the lamp which exhibits a low fluorescence efficiency in the laser medium. By absorbing radiation with the low fluorescence efficiency in the laser medium, heat which develops in the laser medium can be limited to control the thermally induced optical distortions.

Abstract: A longitudinally pumped laser is characterized by one segment in which the cavity mode is astigmatic. A solid state medium is mounted within the one segment, so that a volume of the astigmatic cavity mode within the laser medium defines a cavity mode volume. A pump beam is supplied collinearly with the cavity mode through a means causing astigmatic focusing of the pump beam in the laser medium to define a pumped volume within the laser medium. The astigmatically focusing means is mounted according to a precalculated parameter that achieves the best possible average match of the pumped volume with the cavity mode volume, in light of the physical limitations on layout of the resonant cavity. The one segment may be defined by a first off-axis spherical mirror and a second off-axis spherical mirror, with a Brewster-cut solid state medium mounted in between.

Abstract: An intercalation compound obtained by intercalating a halide of sodium or an element belonging to the group IV of the periodic table such as NaBr, SiCl.sub.4, etc., in a layer crystal substance such as graphite is suitable as an optical resonator in a device for emitting coherent radiation together with an exciting energy supplying means which can radiate synchroton radiation or plasma focus X-rays, particularly in an X-ray laser for emitting X-rays having a wavelength of 10 .ANG. or less.

Abstract: A light emitting element comprising diamond which contains N-V color centers in a maximum optical density of of 0.01 to 3.5 in a direction of excitation light, Ib type nitrogen atoms in a maximum optical density not larger than 0.2 in a wavelength range of 530 to 610 nm and optionally H3 color centers, which element can be efficiently produced from artificial diamond by a combination of irradiation by an electron beam or a neutron beam and annealing.

Abstract: A solid state gain medium is disposed between two mirrors to form a resonant cavity, the cavity length selected so that the gain bandwidth of the gain medium is less than the frequency separation of the cavity modes. By selecting this cavity length, only a single longitudinal mode will oscillate when the laser operates in a single transverse mode. The microlaser is optically pumped by any appropriate source such as a semiconductor injection laser or laser array. Suitable gain media are Nd:YAG and Nd pentaphosphate.

Abstract: A broadly wavelength-tunable laser is provided which comprises as the laser medium a single crystal of MBO.sub.3 :Cr.sup.3+, where M is selected from the group of Sc, In and Lu. The laser may be operated over a broad temperature range from cryogenic temperatures to elevated temperatures. Emission is in a spectral range from red to infrared, and the laser is useful in the fields of defense, communications, isotope separation, photochemistry, etc.

Abstract: The Figure of Merit of titanium-doped sapphire crystal article suitable for use as a tunable laser is enhanced by treating the article at a temperature of about 1750.degree. C. to 2025.degree. C. in an atmosphere containing at least about 20 volume percent hydrogen.

Abstract: A portable laser designator is provided having a highly efficient slab type SGG:Cr:Nd output laser with a phase conjugation mirror and compact folded optical system.

Abstract: Coherent coupling of a plurality of reflection type optical gain elements with a seeding laser is provided by illuminating the optical gain elements with fanned laser light scattered from a photorefractive medium. The reflection type optical gain elements have an anti-reflective end nearer the photorefractive medium and a reflective opposite end. The optical gain elements also illuminate the photorefractive medium. The resultant amplified and coherent light beam has its wavefront cleaned up with a photorefractive oscillator to provide a diffraction limited or nearly diffraction limited beam.

Abstract: A laser emission material containing a solid laser active medium dispersed in a melt molded product matrix of a zeolite.

Abstract: A laser medium is particularly useful in high average power solid state lasers. The laser medium includes a chormium dopant and preferably neodymium ions as codopant, and is primarily a gadolinium scandium gallium garnet, or an analog thereof. Divalent cations inhibit spiral morphology as large boules from which the laser medium is derived are grown, and a source of ions convertible between a trivalent state and a tetravalent state at a low ionization energy are in the laser medium to reduce an absorption coefficient at about one micron wavelength otherwise caused by the divalent cations. These divalent cations and convertible ions are dispersed in the laser medium. Preferred convertible ions are provided from titanium or cerium sources.

Abstract: Chromium doped colquiriite, LiCaAlF.sub.6 :Cr.sup.3+, is useful as a tunable laser crystal that has a high intrinsic slope efficiency, comparable to or exceeding that of alexandrite, the current leading performer of vibronic sideband Cr.sup.3+ lasers. The laser output is tunable from at least 720 nm to 840 nm with a measured slop efficiency of about 60% in a Kr laser pumped laser configuration. The intrinsic slope efficiency (in the limit of large output coupling) may approach the quantum defect limited value of 83%. The high slope efficiency implies that excited state absorption (ESA) is negligible. The potential for efficiency and the tuning range of this material satisfy the requirements for a pump laser for a high density storage medium incorporating Nd.sup.3+ or Tm.sup.3+ for use in a multimegajoule single shot fusion research facility.

Abstract: The invention relates to an improved method of making a beryllium aluminate laser rod wherein a crystal is grown by the Czochraslshi technique by core drilling and grinding. The improvement resides in heat treating the rod to release mechanical stresses induced in the single crystal rod by the griding operation to improve its optical properties. The invention also resides in a rod manufactured in this manner and to a laser employing such a rod.

Abstract: The congruently melting composition of gadolinium scandium gallium garnet comprisesGd.sub.2.96.+-.0.03 Sc.sub.1.90.+-.0.05 Ga.sub.3.14+0.05 O.sub.12.The composition may be used as the substrate for magnetic bubble domain devices or, when doped with a suitable activator (e.g., Cr.sup.+3 or Nd.sup.+3 or both), may serve as the active medium of a solid state laser.

Abstract: A microlaser comprises a solid state gain medium, such as YLF or YAG, positioned end to end with a mode selector etalon formed by a fused silica flat, the end of which is adjacent to a planar end of the gain medium is coated with a thin film of nichrome and the other end of which is coated with a multilayer-dielectric partially-transmissive reflector. The other end of the gain medium is curved and coated to be reflective of the laser light and transmissive of the pump light which enters through such end. The thin nichrome film is designed to absorb unwanted modes which have an electric field component at such film while a wanted mode has a null at such film in their standing wave patterns. By substituting birefringent crystalline quartz for the fused-silica, there may be derived emission at two longitudinal modes whose polarization vectors are orthogonal and whose wavelengths are slightly different.

Abstract: A solid state laser in which molecules containing transition metal ions form the lasing medium. More particularly, the electronic states of molecular complexes containing transition metal ions, which are in closed shell configurations, are pumped by an ultraviolet source to emit coherent radiation.

Abstract: A lighting device is provided for emitting superradiant fluorescent light. First material layers are provided which emit predetermined electromagnetic waves of spontaneous emission when supplied with a predetermined energy (e.g. a pumping ray or beam). Second material layers, transparent to the electromagnetic wave, are stacked between the layers of the first material. To provide an improved light emission, the second material layers are arranged so that the interspaces l between the first material layers are smaller than c.multidot..tau..sub.R, where c is the velocity of said electromagnetic wave and .tau..sub.R is a time constant of the spontaneous emission.

Abstract: A solid state laser medium for use in a solid state laser oscillator uses a hollow cylindrical solid state laser medium which is formed cylindrically in order to improve the cooling efficiency of the laser. The laser includes a pumping device for exciting the laser medium and an optical resonator that is arranged on both ends in the axial direction of the laser medium. The pumping device includes a plurality of flash lamps that are arranged on the outside, with respect to the central longitudinal access of the laser medium, of the outer surface of the hollow cylindrical laser medium and an outer reflector that is arranged so as to enclose the flash lamps and the laser medium, from the outside, with respect to the central longitudinal access of the laser medium, of the flash lamps, and a cylindrical inner reflector with outer diameter which is slightly smaller than the inner diameter of the laser medium, the inner reflector being inserted in the cavity of the laser medium.

Abstract: The invention involves the finding that the congruent composition of any complex oxide is non-stoichiometric.

Abstract: An optical device that stabilizes the power in a cw laser beam comprises a material whose absorption coefficient increases wth increasing incident intensity. The same device acts as an energy limiter and pulse shortener for a pulsed laser. In either case, the device can be located either within the laser cavity or outside it. In another embodiment, the device is placed into the cavity of a passively mode-locked laser to permit mode-locking with laser materials that have high gain-saturation energy. Materials suitable for use in the device include Cr-doped crystalline solids and organic solutions, such as laser dyes, saturable absorber dyes, etc.

Abstract: A single crystal of rare-earth-doped lanthanum beryllate, whose crystal orientation is suitably chosen, provides a laser medium whose index of refraction is substantially independent of temperature. A laser using such a crystal as the laser medium displays little or no thermal lensing, thus permitting high power operation without wavefront distortion.

Abstract: Crystals of neodymium and praseodymium iron garnet materials have Faraday rotation which render such materials suitable for use, e.g., as antireciprocal components in optical devices and communications systems. These materials can be made by liquid-phase epitaxy on a substrate having suitable lattice parameters, deposition being carried out at relatively low melt temperatures.

Abstract: Li.sub.4 Ge.sub.5 O.sub.12 activated by a closed shell ion such as Ti.sup.+4 or Sn.sup.+4 as the active medium for a solid state laser that emits in the blue-green region of the visible spectrum.

Abstract: A laser medium containing a chromium (3+) doped germanate garnet represented by the general formula: Ca.sub.3 M.sub.2(1-x) Cr.sub.2x (GeO.sub.4).sub.3 wherein M is Al.sup.3+, Ga.sup.3+, Sc.sup.3+, Lu.sup.3+, or Y.sup.3+ and 0<x.ltoreq.0.25 is disclosed. A laser employing the above-described laser medium is also described.

Abstract: A new optical parametric oscillator which employs a urea crystal is disclosed. The organic crystal makes the oscillator broadly tunable, so that the entire spectral range from the ultraviolet to the near infrared is accessible.The urea optical parametric oscillator is angle tunable, and has a high efficiency.

Abstract: An optical device that stabilizes the power in a cw laser beam comprises a material whose absorption coefficient increases with increasing incident intensity. The same device acts as an energy limiter and pulse shortener for a pulsed laser. In either case, the device can be located either within the laser cavity or outside it. Materials suitable for use in the device include Cr-doped crystalline solids and organic solutions, such as laser dyes, saturable absorber dyes, etc.

Abstract: A laser amplifier and method as disclosed wherein excitons in a pure insulator or semiconductor crystal are triggered by incident resonant laser radiation. The excitons are created by an external intermittent radiative source, and stimulated decay produces light output at a wavelength characteristic of the crystal. The radiative source produces light at the same wavelength as the light output produced by stimulated exciton decay, thereby producing an amplified output.

Abstract: The invention relates to a novel oxide for tunable lasers. These oxides comply with the formula:(A.sub.1-x X.sub.x).sub.n (B.sub.1-y Y.sub.y).sub.m O.sub.4in whichA represents one or more elements chosen from the group Mg, Mn and Zn;X represents one or more optically active divalent cations chosen from among V, Ni and Co;B represents one or more elements of the same valence chosen in the group comprising Si, Ge, P, Te, W, Al, In, Ga and Mo;Y represents one or more optically active trivalent cations chosen from among Cr, V and Ni;x is such that 0.ltoreq.x.ltoreq.0.15;y is such that 0.ltoreq.y.ltoreq.0.15; andm and n are integers such that 2n+vm=8 with v representing the valence of B, provided that y=0 when B represents one or more elements chosen from among Si, Ge, P, Te, W and Mo and x and y are not both equal to 0.As an example of such oxides, reference is made to Mg.sub.0.99 Ni.sub.0.01 Al.sub.2 O.sub.

Abstract: A solid state laser whose medium is a strontium aluminum fluoride crystal doped with chromium. This laser medium has a wavelength tuning range centered around 850 nm and the laser gain is estimated to be a factor of 2-3 times higher than that of emerald and alexandrite lasers at room temperature.

Abstract: A method of optical pumping of an erbium laser and an apparatus therefor with an erbium laser medium, a light source for side-pumping the erbium laser medium, a neodymium laser medium for emitting a laser beam upon optical pumping by the light source, and an optical system for directing the laser beam from the neodymium laser medium to the erbium laser medium for side-pumping the erbium laser medium. Thus the erbium laser medium is side-pumped by the light source and also end-pumped by the laser beam emitted from the neodymium laser medium side-pumped at the same time by the light source in the same lamp house. Therefore the erbium laser can be optically pumped with high efficiency and offer a low threshold value.

Abstract: An optical sensor for detecting changes in physical quantities such as temperature, position, force, level, pressure, flow, acceleration, magnetic or electrical field strength or mechanical deformation, includes a luminescent material built up of atomically localized luminescence centers, included as a solid solution in an amorphous or mono-crystalline bonding material.

Abstract: A broadly wavelength-tunable laser is provided which comprises as the laser medium a single crystal of YGG:Cr.sup.3+. The laser may be operated over a broad temperature range from cryogenic temperatures to elevated temperatures. Emission is in a spectral range from red to infrared, and the laser is useful in the fields of defense, communications, isotope separation, photochemistry, etc.

Abstract: Stimulated emission at the approximate wave length of 4.5 microns, 2.25 microns and 1.6 microns is obtained from pumping on an excited energy level. The phenomenon of photon avalanching is utilized to create a population inversion within three lower level states that have a substantially equal energy spacing to provide resonance between neighboring ions. This resonance feeds the photon avalanching process when pump having sufficient power in excess of the critical pump power irradiates a LaCl.sub.3 :Pr.sup.+3 crystal at an excited energy level to maintain a population inversion in an optical cavity.

Abstract: A laser system in which the laser medium is a single crystal of Be.sub.3 Al.sub.2 Si.sub.6 O.sub.18 :Cr.sup.3+ (Emerald) is disclosed. Because of its wide fluorescent bandwidth, the material is suitable for high intensity, tunable, mode-locked pulses with durations as short as 10-500 femtoseconds. A number of different laser systems containing this laser medium are described.