Abstract: An infrared laser system includes a neodymium laser for generating a pulsed laser beam at a wavelength of 1.06 micrometers and a Raman cell containing a Raman active medium. The laser beam, having sufficient peak power to cause emission of light from the Raman active medium by stimulated Raman scattering, is directed through the Raman cell. Ethanol-d.sub.1 or methanol-d.sub.1 is used as the Raman active medium to generate wavelengths of about 1.5 micrometers, 2.8-2.9 micrometers, or both. The laser is preferably a neodymium YAG laser.

Abstract: A submillimeter wave-generating integrated circuit includes an array of N photoconductive switches biased across a common voltage source and an optical path difference from a common optical pulse of repetition rate f.sub.0 providing a different optical delay to each of the switches. In one embodiment, each incoming pulse is applied to successive ones of the N switches with successive delays. The N switches are spaced apart with a suitable switch-to-switch spacing so as to generate at the output load or antenna radiation of a submillimeter wave frequency f on the order of Nf.sub.0. Preferably, the optical pulse has a repetition rate of at least 10 GHz and N is of the order of 100, so that the circuit generates radiation of frequency of the order of or greater than 1 Terahertz.

Abstract: An optical transmission system for the transmission of optical signals in a wave-division multiplex on a plurality of neighboring optical carrier wavelengths is characterized by the fiber being doped to form a continuously distributed waveguide amplifier over the entire length of the transmission waveguide. To pump the waveguide amplifier, which is continuously distributed along the transmission waveguide, several arrangements are provided. This system can be operated as a unidirectional system or a bidirectional system.

Abstract: Apparatus for producing laser radiation substantially at 1,444 .mu.m. Embodiments of the present invention are improved structures for neodymium lasers wherein an active laser material is formed in the shape of a rod, a tube, and a slab, including embodiments of a slab laser wherein the slab is pumped by diode arrays. In particular, the improved designs relate to the reflectivities assigned to reflectors which form the laser resonator; the structure of the pumping apparatus (including the shape and composition of the pumping cavity); the concentration of Nd; the dimensions of the active material; the structure of the laser resonator; and the pumping parameters such as pulse duration, pulse rate, and pump energy.

Abstract: Free electron laser apparatus, for producing coherent electromagnetic radiation within a spectral range extending from millimeter to visible wavelengths, includes elements for generating an electron beam and for directing the beam to move over the surface of a diffraction grating, thereby producing electromagnetic radiation. Optical or quasi-optical elements confine the electromagnetic radiation to generate feedback, resulting in stimulated, coherent emission.

Abstract: An infrared laser system includes a neodymium laser for generating a pulsed laser beam at a wavelength of 1.06 micrometers and a Raman cell containing a Raman active medium. The laser beam, having sufficient peak power to cause emission of light from the Raman active medium by stimulated Raman scattering, is directed through the Raman cell. Ethanol-d.sub.1 or methanol-d.sub.1 is used as the Raman active medium to generate wavelengths of about 2.8-2.9 micrometers. The laser is preferably a neodymium YAG laser.

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 Stark-tuned laser operating in the 119 micron line of CH.sub.3 OH has an output power of several tens of milliwatts at 30 Watts of pump power while exhibiting a doublet splitting of about ten MHz with the application of a Stark field on the order of 500 volts/cm. This output power allows for use of the laser in a multi-channel interferometer, while its high operating frequency permits the interferometer to measure rapid electron density changes in a pellet injected or otherwise fueled plasma such as encountered in magnetic fusion devices. The laser includes a long far-infrared (FIR) pyrex resonator tube disposed within a cylindrical water jacket and incorporating charged electrodes for applying the Stark field to a gas confined therein. With the electrodes located within the resonator tube, the resonator tube walls are cooled by a flowing coolant without electrical breakdown in the coolant liquid during application of the Stark field. Wall cooling allows for substantially increased FIR output powers.

Abstract: A millimeter wave power generator combines two laser beams, tuning the beat frequency to the desired millimeter wave value with an opposing pair of millimeter wave cavities. The combined beam is diffracted onto a plurality of externally powered, modulation doped field effect photodetectors (MDFEPs). A plurality of antennas is provided, one between each pair of adjoining MDFEPs. The antennas are parallel, and each is driven by the MDFEPs at its ends. The back propagating millimeter wave radiation is reflected forward by a wire grid parallel to the antennas. The grid is situated between the diffractor and the MDFEPs, and is spatially tuned to constructively interfere the reflected back propagating with the forward propagating millimeter wave radiation.

Abstract: Tunable far infrared radiation is produced from two-dimensional plasmons in a heterostructure, which provides large inversion-layer electron densities at the heterointerface, without the need for a metallic grating to couple out the radiation. Instead, a light interference pattern is produced on the planar surface of the heterostructure using two coherent laser beams of a wavelength selected to be strongly absorbed by the heterostructure in order to penetrate through the inversion layer. The wavelength of the far infrared radiation coupled out can then be readily tuned by varying the angle between the coherent beams, or varying the wavelength of the two interfering coherent beams, thus varying the periodicity of the photoconductivity grating to vary the wavelength of the far infrared radiation being coupled out.

Abstract: A gas laser 10 has a gas-field enclosure 12 in which electrodes 14, 16 are operable to excite the gas within the enclosure to emit laser radiation. The region 20 between the electrodes 14, 16 contains a plasma which emits the laser radiation. At one end of the enclosure 12, there is a plasma-free region 22 undivided from the region 20. A microphone 24 is located in the plasma-free region 22. This detects pressure waves occurring in the plasma-free region when laser radiation is absorbed. The signal from the microphone is used to control a feedback circuit 26 to stabilize the frequency of the emitted laser radiation.

Abstract: A FIR Laser cavity comprising a pair of concentric tubes of heatproof dielectric, a pair of nozzles intended for circulating within the space between said pair of tubes a refrigerating and thermally stabilizing fluid; a pair of laser heads disposed at the two ends of said tubular assembly which heads are provided with optical elements; a differential thread sleeve mounted concentrically with said tubes and intended for obtaining the longitudinal micropositioning of one of said heads with respect to one another; two series of three screws which are mounted with a starlike symmetry on said heads and intended for allowing a fine adjustment of the optics carried by said heads along two axes perpendicular to one another and with respect to the geometrical axes of said tubes by means of the elastic deformation of an O ring which is interposed between each head and the tubular body and an output optics carrier and comprising either a reflector and a window for the hermetic seal, or by the reflector alone, which is g

Abstract: The laser has three regions p-n-n+ or n-p-p+ of magnetic element alloyed Group II-VI elements such as Cd, Hg, and Te doped with an element having a high atomic radius such as Sb or In. The magnetic element may be Mn or Fe. Vapor phase epitaxy is used to create a substrate having graded energy band gap characteristic across its thickness. A two-step liquid phase epitaxy process is used to grow an active layer and a passive layer to create the laser heterostructure. The index of refraction of the active region is higher than the indexes of refraction of the substrate and passive regions. The graded energy band gap and high doping of the substrate region results in a very low resistance which minimizes a temperature rise resulting from joule heating at high current densities. The relationship of the indexes of refraction of the layers result in double sided optical confinement to support lasing. In a semimagnetic semiconductor such as HgMnTe, the coefficient dE.sub.

Abstract: A source of coherent blue light comprises a diode laser for pumping a Nd.sup.3+ doped member of lasant material disposed within an optical resonator for exciting the .sup.4 F.sub.3/2 -.sup.4 I.sub.9/2 laser transition of a wavelength within the range of 0.870 to 0.960 .mu.m. The laser radiation within the optical resonator is doubled by means of a doubler crystal of a non-linear, electro-optic material to produce blue light which is then extracted from the optical resonator as an output beam. A thermo-electric cooler is coupled in heat-exchanging relation with the Nd.sup.3+ doped laser material to improve the efficiency and the doubler crystal is temperature controlled for phase matching to the laser radiation within the range of 0.870 to 0.960 .mu.m. The diode pump laser is preferably either a GaAlAs or GaAs diode laser producing pumping radiation of a wavelength of approximately 0.810 .mu.m.

Abstract: A novel design for an RF pumped gas laser is provided by spiralling an RF in lead transmission line around a ceramic gas container. The pitch of the spiral and spacing between the leads of the transmission line are chosen to produce currents parallel to the axis of the spiral to provide more efficient energy transfer modes between the pump and the lasing gas.

Abstract: A solid state cyclotron laser device generate coherent electromagnetic radiation. A semiconductor configuration comprises an emitter region and a collector region separated by a base region and barrier layers on each side of the base. The semiconductor configuration is biased such that electrons enter the base region from the emitter region as hot electrons. A magnetic field applied by an external source to the base region causes the hot electrons to gyrate and quantize into Landau levels. An optical resonance cavity produces standing wave modes which stimulate the electrons to move from higher to lower Landau levels to generate conherent radiation. Electrons with decreased energy are removed at the collector in order to maintain the population inversion. The device is tunable by adjusting the magnetic field.

Abstract: The disclosed source of coherent radiation is of the type adapted to provide an inversion layer of electrons. The preferred embodiment comprises a grated MOSFET having gallium arsenide or indium antimonide substrate so as to provide a source which is (1) operable at room temperatures, and (2) self-exciting in response to predetermined, substantially constant DC current levels of gate voltage and source-drain voltage.

Abstract: A far-infrared laser structure is provided wherein a uniform longitudinal ectric field mode is provided for a radio frequency pump by means of a set of fully or near-fully circular ring shaped electrodes.

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 method is described for generating tunable far-infrared radiation. The apparatus includes a Schottky-barrier diode which has one side coupled through a conductor to a waveguide that carries a tunable microwave frequency, the diode having an opposite side which is coupled through a radiating whisker to a bias source. Infrared light is directed at the diode, and infrared light with tunable sidebands is radiated by the whisker through an open space to a reflector. The original infrared is separated from a tunable infrared sideband by a polarizing Michelson interferometer.

Abstract: A method and apparatus for reducing gas pressure in a laser wherein a miniature cryogenic pump is constructed to comprise an integral part of a laser plasma tube. The pump includes a container which holds molecular sieve material, a conduit which permits communication between the container and the plasma tube, and a valve which controls the communication along the conduit. All connections between the container, conduit, valve and plasma tube are gas-tight so as to maintain the ion integrity of the plasma tube with respect to the atmosphere. In operation, a service engineer immerses the container in a refrigerant, such as liquid nitrogen, and opens the valve until the pressure in the plasma tube reaches the desired level. Thereafter the valve is closed and the container permitted to return to ambient temperature. Further in accordance with the present invention, means are provided for preventing over pressure in the container.

Abstract: Apparatus and method for generating continuous wave 16 .mu.m laser radiation using gaseous CF.sub.4. Laser radiation at 16 .mu.m has been observed in a cooled static cell containing low pressure CF.sub.4 optically pumped by an approximately 3 W output power cw CO.sub.2 laser. The laser cavity employed was a multiple-pass off-axis-path two spherical mirror ring resonator. Unidirectional CF.sub.4 laser output power at 615 cm.sup.-1 exceeded 2 mW. Computer calculations indicate that for modest pump powers of about 40 W, approximately 1 W of emitted laser radiation at 16 .mu.m might be obtained.

Abstract: A cryogenic infrared laser in deuterium in which an output is produced by exciting the deuterium after it has been cooled to cryogenic temperature with a high voltage pulse discharge to produce laser action in three or more lines as output pulses with varying lengths and with wavelengths in the 4 .mu.m band and including 4.52 .mu.m, 4.60 .mu.m, and 4.71 .mu.m.

Abstract: A far-infrared electromagnetic wave generator comprises a semiconductor containing at least one impurity which has an energy difference, close to a quantum energy of optical phonon, between its transition levels; a resonator having two reflectors for effecting positive feedback of an electromagnetic wave corresponding to the quantum energy; and means for applying an electric current across the semiconductor. The semiconductor may have p-i, n-i, p-i-n, p-n, or n-p.sup.- junction. One of the reflectors of the resonator may have a diffraction grating so that the wavelength of the electromagnetic wave to be generated can be varied by adjusting an angle of the diffraction grating.

Abstract: A synergistic quasi-free electron laser for generating infrared radiation. The laser includes a means for producing a volume of ionized gas plasma, a means for directing an electron beam through the gas plasma in a first direction, and a means for directing a laser pump beam into the gas plasma in a second direction opposite to the first direction to produce synergistic bunching of the electron beam and the ionized gas plasma. A portion of the laser pump beam is backscattered by the bunched electron beam and gas plasma to form an output beam having a frequency up-shifted from that of the laser pump beam. The frequency of the output beam may be tuned by changing the velocity of the electron beam.

Abstract: A source of coherent electromagnetic radiation capable of generating or amplifying waves in the centimeter, millimeter, and submillimeter wavelength range. An annular beam of gyrating electrons is produced which is then compressed to its paraxial position by means of a solenoid magnetic field around the wave-guide. This electron beam is also subjected to a transverse motion in an interaction region by a longitudinal rippled (wiggler) magnetic field. Such a field is generated by a periodic assembly of rings magnetized in the axial direction. The electron beam during its accelerated motion generates or amplifies coherent electromagnetic radiation in the centimeter, millimeter, or submillimeter range.

Abstract: A new Raman gain medium, comprising an optical fiber into which molecular gas has been diffused, is disclosed. This new medium combines the advantages of a fiber, i.e., long interaction path, low loss, controllable dispersion, and convenience in handling, with the large Raman wave number shift of the gas, i.e., 4136 cm.sup.-1 for H.sub.2 in silica. A laser made with such a medium can provide a relatively high power, tunable, coherent signal source in the near and far infrared regions.

Abstract: The operation of a two-photon, three level laser system at high temperatures or pressures is made possible by reducing the build up time of the flux of the second lasing transition in the laser discharge region.

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: 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 gas laser adapted to produce laser radiation in the far infrared region of the electromagnetic spectrum, but adapted, as well, to produce radiation in the infrared, the near infrared, the millimeter and the microwave regions. The laser employs a zig-zag pumping scheme which serves to excite the gas uniformly and thus enhance transfer of pump energy into laser energy.

Abstract: An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.