Abstract: A fibre laser (1) of the type comprising a doped single-mode optical fibre (3) arranged between reflectors (5,7), and which is coupled (11) to an optical pumping source (9). For the given reflection efficiency of the reflectors (5,7), the length of the optical fibre (3) is chosen such that it exceeds that affording saturation and provides at its end a region for absorption (FIG. 1). The resultant hysteretic behavior of this bistable device may be utilized for logic memory (bistable), and regenerative amplification applications. To this end a second source (9') can be coupled (11',19) to the laser fibre (3).

Abstract: An optically pumped laser which includes a laser diode array for generating optically pumped radiation having a uniform intensity distributed over a broad band-width, and a lasant material with an absorption band for receiving radiation within such bandwidth.

Abstract: An intracavity frequency-modified laser of improved amplitude stability is obtained through the use of a plurality of nonlinear optical crystals within the laser cavity. Extremely low noise operation of such a multiple crystal laser is achieved by measuring the noise in its output radiation as a function of the temperature of its optical cavity and maintaining the cavity temperature at a value that results in low noise production during subsequent operation.

Abstract: A miniaturized Q-switch is added to the resonant cavity of a compact laser diode pumped solid state laser to produce short high peak power pulses which are input into a single mode optical fiber to form a compact continuum generator. Q-switching the compact laser diode pumped solid state lasers takes advantage of the relatively high gain and short cavity length to provide a desirable combination of pulsewidth and pulse energy. Nd:YAG or Nd:YLF are useful solid state laser materials for Q-switching, or other longer lifetime rare earth ions such as erbium or holmium for greater energy storage. The Q-switch is formed of a material such as TeO.sub.2, SF.sub.10, or LiNbO.sub.3 with an acoustooptic figure of merit substantially greater tha fused silica. The high peak powers of the lasers are sufficient to exceed the threshold for Raman conversion in the fiber which produces a series of red shifted bands ending in a continuum by stimulated Raman scattering.

Abstract: A diffractive lenslet array receives light from multiple lasers. The lenslet array is spaced apart from a partially reflecting mirror by a distance Z=nd.sup.2 /.lambda. where n is an integer or half integer, .lambda. is the laser wavelength and d is the spacing of the lenslets in the array. In a preferred embodiment the apparatus is a unitary design in which the lenslets are etched into one surface of a substrate and a parallel surface is coated to form the partially reflecting mirror. The lenslets abut one another to produce a fill factor (percentage of array containing light) close to one and each of the lenslets is a multistep diffractive lens. Diffractive speading over a round trip distance from lasers to mirror and back again causes feedback light from a single lenslet to couple into adjacent lenslets.

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: The invention relates to an optical manifold permitting a single pumping source to be utilized to selectively pump a plurality of laser sources. Switching of the emission from the pumping source to the laser source is accomplished by a plurality of FTIR switches. A second group of FTIR switches is utilized to switch the output beams of the laser sources to a common output path.

Abstract: A laser having a combination of end and side pumping so as to produce high power pulsed output with little or no delay between side pump pulses and laser output pulses, with suppressed spiking due to gain switching, and with high modulation rates. An active medium, such as a solid state laser rod, in a resonant optical cavity is pumped by a first optical pump source directing radiant energy into an end of the active medium so as to encourage or establish lasing operation in a desired transverse cavity mode, such as the TEM.sub.00 mode. A second optical pump source directs additional radiant energy into a side of the active medium so as to amplify the intensity of the laser output in the desired mode.

Abstract: An optical fiber laser comprising a gain cavity in the form of a single mode optical fiber with integrally formed dichroic mirror end sections to provide feedback. The fiber core comprises a host material of silicate glass preferably doped with 0.01 to 1 weight percent of just erbium oxide as a lasing medium. The laser is end pumped at approximately 1.49 micrometers with a laser diode, preferably InGaAsP, and has an output at 1.54 micrometers.

Abstract: An injection locked oscillator system for pulsed metal vapor lasers is disclosed. The invention includes the combination of a seeding oscillator with an injection locked oscillator (ILO) for improving the quality, particularly the intensity, of an output laser beam pulse. The present invention includes means for matching the first seeder laser pulses from the seeding oscillator to second laser pulses of a metal vapor laser to improve the quality, and particularly the intensity, of the output laser beam pulse.

Abstract: A miniaturized Q-switch is added to the resonant cavity of a compact laser diode pumped solid state laser to produce short high peak power pulses. Q-switching the compact diode pumped solid state lasers takes advantage of the relatively high gain and short cavity length to provide a desirable combination of pulsewidth and pulse energy. Nd:YAG or Nd:YLF are useful solid state laser materials for Q-switching, or other longer lifetime rare earth ions such as erbium or holmium for greater energy storage. The Q-switch is formed of a material such as TeO.sub.2, SF.sub.10, or LiNbO.sub.3 with an acoustooptic figure of merit substantially greater than fused silica. Pulsewidths of 10-50 ns are achieved at pulse energies of 10-20 microjoules. TEMOO output is easily produced by the compact laser pumped solid state resonator. Applications include materials processing, link blowing in semiconductor memories, marking and scribing, and optical time domain reflectometry.

Abstract: A laser for generating a coherent output beam with a frequency equal to the um or difference of the frequencies of two input pumping beams or the harmonics thereof. The laser includes a lasing medium of the type with an inverse Faraday effect resonance frequency f.sub.1, a laser cavity with the lasing medium positioned therein, two coherent light sources for generating pumping beams at frequency f.sub.1 and f.sub.2, where the f.sub.1 beam is circularly polarized, and an optical system for directing the pumping beams into the lasing medium.

Abstract: A second harmonic, optical generator is disclosed in which a laser diode produces an output pumping beam which is focused by means of a graded, refractive index rod lens into a rod of lasant material, such as Nd:YAG, disposed within an optical resonator to pump the lasant material and to excite the optical resonator at a fundamental wavelength. A non-linear electro-optic material such as MgO:LiNbO.sub.3 is coupled to the excited, fundamental mode of the optical resonator to produce a non-linear interaction with the fundamental wavelength producing a harmonic. In one embodiment, the gain medium and the non-linear material are disposed within an optical resonator defined by a pair of reflectors, one of which is formed on a face of the gain medium and the second of which is formed on a face of the non-linear medium. In another embodiment, the non-linear, electro-optic material is doped with the lasant ion such that the gain medium and the non-linear doubling material are co-extensive in volume.

Abstract: A diode pumped Nd:YAG laser is disclosed. The YAG rod is coated on its ends to define an optical resonator containing the YAG rod. The YAG rod is made sufficiently short, i.e., 1 mm, so that it will support only two axial resonant (lasing) modes. The rod is transversely stressed to polarize the two original modes and to excite a third lasing mode orthogonally polarized to the first two modes. The third mode is separated from the first two modes to provide stable, single mode TEM.sub.001 output. The transverse stress is applied by means of a spring clamp made of a material, Be-Cu, having a low temperature coefficient.

Abstract: A monolithic phasematched harmonic generator is obtained by optically pumping an optically nonlinear lasant member having reflective faces defining the monolithic optical resonator. Phasematching is achieved, in one case, by inclining a totally internally reflective face of the resonator at a proper angle relative to other faces of the resonator to angularly separate and resonate lasant waves of the proper polarization. In a second case, a clad fiber resonator of optically nonlinear lasant material has its cladding arranged to guide and thus resonate only lasant waves of the correct polarization. In a third case, the optical nonlinear coefficient of the optically nonlinear lasant material is spatially modulated with a period equal to an odd integer number of coherence lengths, of the harmonic generation process, to obtain quasi-phasematched operation. Phasematched operation improves the efficiency of the harmonic generation process.

Abstract: An optically pumped solid state laser which is constructed of components held in association by a support structure which is configured to receive the components and automatically arrange them with respect to one another along an optical path.

Abstract: An optically pumped solid state laser which is constructed of components having attached fittings which are structured in such a manner that the components are automatically arranged with respect to one another along an optical path upon joining the fittings together.

Abstract: A relatively low-power but high-quality laser oscillator is coupled to a high-power laser amplifier. The amplifier includes a rectangular slab of laser active material, and a phase-conjugate end mirror.

Abstract: A neodymium or other rare earth doped solid state laser is pumped by a matched high efficiency laser diode, resulting in a compact, high efficiency and long lifetime laser assembly. Output is in the near infrared range, but can be converted to the visible spectrum by an intra-cavity frequency doubler. A doubling crystal, which may be a KTP crystal, is placed at an optimum location in the laser cavity. Polarization of the beam may be achieved simply by stressing a non-birefringent rod, prior to frequency doubling, or by using a birefringent material such as Nd:YLF for the rod. An amplitude noise suppression elaton may also be placed at an optimum position in the laser cavity; alternatively a ring cavity or pair of quarter wave plates can be used. A folded cavity configuration produces a pair of beam waists in the cavity. Pulsed operation can be produced by means of a Q-switch.

Abstract: A low-divergence 1.06 micrometer wavelength beam from a total-internal-reflection, face-pumped laser (TIR-FPL) is focused onto the end of a quartz optical fiber to a spot having a size smaller than the fiber diameter and with a beam cone angle less than twice the numerical aperture of the fiber. The fiber transmits the energy to emerge at the other end where it is collimated and focused onto material to be processed. A laser average output power level greater than 400 watts can be transmitted through an optical fiber having a diameter less than 600 micrometers.

Abstract: A neodymium or other rare earth doped solid state laser is pumped by a matched high efficiency laser diode, resulting in a compact, high efficiency and long lifetime laser assembly. Output is in the near infrared range, but can be converted to the visible spectrum by an intra-cavity frequency doubler. A doubling crystal, which may be a KTP crystal, is placed at an optimum location in the laser cavity. Polarization of the beam may be achieved simply by stressing a non-birefringent rod, prior to frequency doubling, or by using a birefringent material such as Nd:YLF for the rod. An amplitude noise suppression etalon may also be placed at an optimum position in the laser cavity; alternatively a ring cavity or pair of quarter wave plates can be used. A folded cavity configuration produces a pair of beam waists in the cavity. Pulsed operation can be produced by means of a Q-switch.

Abstract: A neodymium YAG laser is pumped by a matched laser diode of high efficiency, resulting in a compact, high-efficiency and long-lifetime laser assembly. Output is in the near infrared range, but can be converted to the visible spectrum by an internal frequency doubler. A doubling crystal, which may be a KTP crystal, is placed at an optimum location in the laser cavity. Polarization of the beam may be achieved simply by stressing the YAG rod, prior to frequency doubling.

Abstract: The present invention relates to a specific holding structure of a slab geometry crystal for a total internal reflection, slab geometry laser (otherwise known as face pumped laser) device. Both sides of the crystal are held by side rails, and on both longitudinal end portions of the crystal o-ring backing flanges and box-shaped end pieces, respectively, are put on. Furthermore, an o-ring is put in between the end piece and the o-ring backing flange on each end portion of the crystal, and it is compressed to seal the crystal. This o-ring can be made of translucent elastomer. Accordingly, the slab geometry laser device that is compact and easy to remove from, or place into the pump station is provided.

Abstract: The use of slabs having end faces cut at substantially the critical angle in three different embodiments of a slab laser provides benefits not possessed by conventional cylindrical active lasing mediums or by slab active lasing mediums having end faces cut at Brewster's angle.

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: Apparatus is disclosed for upconverting a laser spanning the near IR region into the near UV region. An alkali halide, for example, NaI, is photodissociated via a coherent or an incoherent pump source, for example, and ArF excimer laser or an ArF excimer flashlamp. A near IR laser, for example, a CO.sub.2 laser, is then focused into a cell containing the photodissociated Na (Na*), thereby producing anti-Stokes Raman emission in the near UV region.

Abstract: A solid-state non-planar internally-reflecting ring laser is described including a single piece of solid state laser material which incorporates at least two mirrored surfaces oriented to change the plane of incidence of the propagating ray path to define a ray path having at least four segments defining at least two planes, when the prism is located in a magnetic field of sufficient strength, the laser will lase in a single longitudinal and transverse mode, the magnetic field decoupling the counter propagating waves.

Abstract: A kilowatt average power solid state laser employs a reciprocating slab of Nd:glass to effectively average the thermal loading thereof.

Abstract: A fiber optic amplifier utilizes a crystal fiber of laser material to bidirectionally amplify light signals. This amplifier permits the application of both pumping illumination and the signal to be amplified to the end of the crystal fiber to avoid the disadvantages inherent in side pumping this fiber. End pumping is accomplished by taking advantage of the slow spontaneous fluorescence of the laser crystal to sequentially apply the pumping illumination and then the signal to be amplified to the crystal. This sequential application of signals is made possible through the use of a switchable coupler which allows light to be selectively coupled from either of a pair of input optical fibers to a single output optical fiber which is coupled to the crystal fiber. The pumping illumination is initially supplied to the crystal fiber to invert the ions within the crystal.

Abstract: A total internal reflection, face pumped laser is provided, in a single head, with two (or more) generally parallel, spaced apart hosts for providing a higher average power output than the typical single host FPL. A pair of flash lamps, one each adjacent the outer surface of each host, acts as the "pumping" means for the laser and operates in effect to produce asymmetrical pumping of the respective hosts. In order to prevent exceeding the thermal stress limit and thermally inducing bending of the hosts, a system of asymmetrical cooling is provided whereby a greater flow of fluid coolant is provided the surfaces of the two hosts which are closer to the "pumping" flash lamps than to the inner host surfaces which are proximate one another.

Abstract: A laser construction is described having a single resonator structure for both a dye laser optical cavity and one or more pump laser optical cavities. In the described embodiments, such resonator structure is formed principally from a plurality of parallel rods.

Abstract: Laser radiation whose wavelength is in the submillimeter wave spectral region is sent through an intercavity dielectric tube positioned inside a coil. The tube contains a gas having large dipole moments and which may be of the same kind as the input beams lasing gas. In response to current therethrough the coil produces an axial magnetic field. The direction of the magnetic field is parallel to the propagation of light transmitted through the dielectric tube. The frequency of the submillimeter wave laser radiation in the tube is shifted from its normal value. The amount of shift is determined by the current in the coil since the resulting magnetic field produces a change in the mean index of refraction of the gas. Thus, the change in index of refraction causes a shift in the laser radiation frequency because the gas within the coil is also located within the submillimeter wave lasing cavity.

Abstract: A preconditioning beam is used to excite gas particles preferentially along a channel between two electrodes in a laser chamber. The preconditioning beam may be an electron beam or a laser beam. An electrical discharge between the electrodes is conducted along the channel by the excited gas particles to form a gas embedded plasma pinch. Depending on the profile of the discharge, the pinch may be stable or collapsing. The pinch emits vacuum ultraviolet radiation which photodissociates molecules of the photolytic laser medium confined by the chamber. The dissociation creates a population inversion, initiating lasing activity. A resonator system reflects the developing laser pulse back and forth through the chamber to stimulate further emissions and facilitate pulse amplification. The developed pulse is transmitted by appropriate means.

Abstract: Disclosed is a coherently optically pumped laser system wherein a pump laser beam (30) propagates through a laser medium contained in a degenerate cavity resonator (10) in a controlled multiple round trip fashion in such a way that the unused pump beam (30') emerges from an injection aperture (24) at a different angle (.beta.) from which it enters (.alpha.) the resonator. The pump beam (30) is angularly injected off of the central axis (22) of the resonator body (10) whereupon the pump beam alternately undergoes spreading and focusing (b.sub.1 . . . b.sub.8) while pumping the laser medium by a process of resonant absorption pumping. Means (32) are employed externally of the cavity resonator to sense the emergent output beam (30') which is used not only for alignment of the system but also to monitor the power of the emergent pump beam. The power in the emergent pump beam (30') provides a measure of the performance of the laser systems.

Abstract: A heterodyne laser ranging system is disclosed which provides a waveguide housing which includes a first and second gas laser. The first laser is a low pressure laser while the second laser is a high pressure laser. These two lasers formed in the waveguide housing have their longitudinal axis in optical alignment. In the preferred embodiment, the second high pressure gas laser is a transversely excited atmospheric (TEA) laser. The first low pressure gas laser produces two outputs, one of the outputs is a low level local oscillator signal while the second output is transmitted as an input to the high pressure laser. The second high pressure laser builds up from the injected signal from the low pressure laser which results in a high pressure laser pulse output that has the frequency stability of the low pressure laser while maintaining the high peak power output available from a transversely pumped waveguide laser.

Abstract: An improved laser apparatus is provided wherein a laser and a pump source comprising an array of GaAs or GaAlAs light emitting laser diodes or of excimer fluorescors or lasers which emits a large cross section beam of generally collimated pumping radiation are coupled by flux concentrating means comprising a compound parabolic concentrator.