Abstract: A laser method of and apparatus for providing a wide variety of laser wavelenghts wherein a pump source of laser radiation is sequentially Strokes-shifted in two separate cells each containing a different molecular or atomic Raman active gas, wherein each cell is optimized to produce primarily first-Stokes radiation as by variation of focal length parameters and/or gas pressure, filter means are provided at the output of the first cell to reject the pump laser radiation and to pass the first-Strokes radiation of the first cell and further filter means are provided at the output of the second cell to reject the first-Stokes radiation of the first cell and pass the first-Stokes radiation of the second cell to provide a desired output laser radiation.

Abstract: An anti-Stokes Raman laser is disclosed which is tunable in the ultraviolet (UV) by utilizing ground state neutral indium atoms as the lasing medium. A photodissociator is utilized to create a metastable indium population and a tunable dye laser is subsequently used to pump the metastable population to an intermediate level. Stimulated anti-Stokes Raman lasing occurs from this intermediate level, thereby generating anti-Stokes Raman emission at 410 nm. Since the dye laser is tunable, the Raman lasing output is tunable over a comparable range.

Abstract: Mono-pulses of light are generated by time compression of laser energy. A Raman medium is located in a low Q energy storage cavity having low losses for light at a predetermined frequency and energy delivered by a laser is that frequency in the storage cavity. The Raman medium is also located in a Stokes cavity dimensioned for having a high gain at a Stokes frequency. Most of the stored energy at the Stokes frequency is extracted by a single to and fro travel through the Stokes cavity.

Abstract: Method and apparatus for switching energy out of a Raman laser optical cavity. Coherent radiation at both the pump and first Stokes wave frequencies are introduced into the optical cavity from the same direction, and a second Stokes wave is utilized to switch the energy out of the cavity.

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 Raman oscillator and amplifier utilizing a single Raman cell. The oscillator and amplifier portions of the cell are located either coaxially or adjacent to each other within a single Raman cell so as to provide a more compact arrangement. In Raman oscillator/amplifier systems employing high-temperature ovens, the invention also reduces heating requirements.

Abstract: A radiation pump recovery system for a double pass pump Raman oscillator is described incorporating a polarizer and quarter waveplate positioned in the optical path of the input pump radiation and functions to separate the reflected pump radiation coming back from the Raman oscillator along the input optical path from said input optical path. In an alternate embodiment the recovery system may include an additional quarter waveplate and mirror to permit unpolarized pump radiation to be separated into two polarizations to drive two Raman oscillators and whereby the reflected pump radiation coming back from the Raman oscillators along the respective input optical paths is separated from said respective input optical path and recombined into a single beam. An alternate embodiment utilizes the rejected pump energy in a Raman amplifier to provide optimal conversion efficiency.

Abstract: Method and apparatus for use of a Raman or Brillouin switch together with a conventional laser and a saturable absorber that is rapidly bleached at a predetermined frequency .nu.=.nu..sub.0, to ultimately produce a Raman or Brillouin pulse at frequency .nu.=.nu..sub.0 .+-..nu..sub.Stokes.

Abstract: Apparatus for simultaneous laser pulse amplification and compression, using multiple pass Raman scattering in one Raman cell and pulse switchout from the optical cavity through use of a dichroic device associated with the Raman cell.

Abstract: A Brillouin ring laser comprises a fiber optic resonator formed from a loop of fiber optic material and a fiber optic directional coupler for optically closing the loop.

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: An anti-Stokes Raman up-converter is disclosed which is capable of up-converting a variety of conventional laser sources. A metal-halide, for example, thallium chloride or thallium iodide, is employed as a lasing medium, and is photodissociated to create a population inversion in a metastable state of the metal ion. An excimer laser, for example, and ArF* or KrF* excimer laser, may be employed to photodissociate the metal-halide in accordance with the present invention. Alternatively, an excimer flashlamp, for example a ArF* or KrF* flashlamp, may be employed to photodissociate the metal-halide in accordance with the present invention. A conventional laser source, for example a CO.sub.2 laser or any harmonic of a Nd:YAG laser, is subsequently employed to pump the population inversion from the metastable state to a virtual level near an intermediate state. Anti-Stokes Raman lasing occurs from this virtual state, where the lasing frequency is greater than the frequency of the conventional laser pump source.

Abstract: An anti-Stokes Raman laser which uses a metastable level of bromine is provided. A medium of molecules each of which contains at least one bromine atom is provided. Means are provided for dissociating the bromine atom from the molecules so that a majority of dissociated bromine atoms go into at least one excited metastable state. Means are provided for jumping the bromine atoms in the metastable state with pump photons in order to provide anti-Stokes Raman output photons by transition from the metastable state to a final state. The output photons have energy equal to the pump photon energy plus an energy gain given by the energy difference between the metastable state and the final state.

Abstract: A crystalline array wherein selected segments thereof can be selectively energized from a primary state to a secondary state; selectively de-energized from the secondary state back to the primary state; and selectively probed to determine whether the sector selected is in the primary or secondary state. The device is capable of being utilized as a switching device.

Abstract: An anti-Stokes Raman laser is disclosed which is tunable over a range of 10-70 cm.sup.-1. An alkali halide is used as the lasing medium and a metastable halide population inversion is created with respect to the ground state of the halide by selective photodissociation of the alkali halide. A pump laser is then employed to move the population from the metastable state to a region near an intermediate state of the halide. The population subsequently falls back to the initial ground state, thereby creating the anti-Stokes Raman emission. Since the intensity of the photodissociation is directly proportional to the amount of population inversion achieved, and hence, to the region the population may be pumped to, the tuning of the output anti-Stokes Raman lasing is a function of the intensity of the initial photodissociation.

Abstract: An auto-ionization pumped anti-Stokes Raman laser is disclosed which is capable of creating a population inversion between the ground state and a metastable state of an ionic lasing material. The lasing material is first pumped above a metastable energy level, where it subsequently falls via auto-ionization back to the metastable level. A second laser pump is employed to move the population from the metastable state to a region near an intermediate state of the lasing material. The population subsequently falls back to the initial ground ionic state, thereby creating the anti-Stokes Raman emission.

Abstract: A regenerative ring amplifier and regenerative ring oscillator which function to feed back a portion of the Stokes signal to complete the ring cavity. The ring cavity configuration allows the CO.sub.2 laser pump signal and Stokes signal to copropagate through the Raman capillary waveguide amplifier. A Raman capillary waveguide amplifier is also provided in the return leg of the ring cavity to increase gain without increasing the round trip time. Additionally, the ring cavity can be designed such that the amplifier Stokes signal is synchronous with the mode-locked spikes of the incoming CO.sub.2 laser pump signal.

Abstract: A combination regenerative ring and backward Raman waveguide amplifier and a combination regenerative ring oscillator and backward Raman waveguide amplifier which produce Raman amplification, pulse compression, and efficient energy extraction from the CO.sub.2 laser pump signal for conversion into a Stokes radiation signal. The ring cavity configuration allows the CO.sub.2 laser pump signal and Stokes signal to copropagate through the Raman waveguide amplifier. The backward Raman waveguide amplifier configuration extracts a major portion of the remaining energy from the CO.sub.2 laser pump signal for conversion to Stokes radiation. Additionally, the backward Raman amplifier configuration produces a Stokes radiation signal which has a high intensity and a short duration. Adjustment of the position of overlap of the Stokes signal and the CO.sub.2 laser pump signal in the backward Raman waveguide amplifiers alters the amount of pulse compression which can be achieved.

Abstract: A device is disclosed for producing a pair of synchronized intense 16 micron pulses in which stimulated rotational Raman scattering together with four wave mixing and pulse compression takes place in parahydrogen on an off-axis path between a pair of spherical mirrors.

Abstract: A gaseous Raman conversion medium is placed inside a laser resonant cavity to generate tunable laser radiation in the visible, near infrared and far infrared spectral ranges with an improved conversion efficiency and a higher power output. The combination of the laser medium, a gaseous Raman medium and nonlinear sum and difference generation using intracavity conversion produces coherent radiation at a frequency distinct from the frequency emitted by the laser medium. This new frequency is coupled out of the cavity as the desired output.

Abstract: An optically pumped isotopic ammonia laser system which is capable of producing a plurality of frequencies in the middle infrared spectral region. Two optical pumping mechanisms are disclosed, i.e., pumping on R(J) and lasing on P(J) in response to enhancement of rotational cascade lasing including stimulated Raman effects, and, pumping on R(J) and lasing on P(J+2). The disclosed apparatus for optical pumping include a hole coupled cavity and a grating coupled cavity.

Abstract: A laser stimulated Raman molecular beam time and frequency standard utilizing a first electromagnetic beam at a first preselected frequency to pump a molecular beam at a first preselected point along the beam to state select the beam. A second electromagnetic beam (produced from either a different electromagnetic source than utilized to produce the first beam or produced from a portion of the first beam) at a second preselected frequency and a third electromagnetic beam at the first frequency simultaneously pump the molecules of the state selected molecular beam at a second point along the beam in a stimulated Raman process. By locking the frequency difference of the first and second electromagnetic beams to a specific resonant frequency, a time and frequency standard can be produced.

Abstract: The present invention relates to a means for generating a broadband source of picosecond radiation in the visible and near-infrared spectral regions. In operation, picosecond pulses with wavelength .lambda. are supplied by a laser pump source (10) and injected into the liquid core of a single mode optical fiber (18). A broadband continuum is generated in the liquid core by two mechanisms. Stimulated Raman scattering in the liquid core of the optical fiber shifts the wavelength of the incoming radiation by an amount equal to the energy of the vibrations in the liquid molecules, where with sufficient power, multiple shifts are possible. In addition, the pump radiation and the shifted radiation are broadened by self-phase modulation thereby "filling" the region between the discrete shifted lines. The output radiation from the optical fiber is, therefore, a broadband tunable picosecond pulse source.

Abstract: The present invention relates to a system for generating extreme ultraviolet (XUV) radiation. The process utilizes pulsed plasmas to create a high density of ions in which non-linear frequency upconversion into the XUV region can occur. In particular, metals are utilized as the lasing medium in the present invention, since the ions of these metals do not absorb wavelengths in the XUV region and a significant level of XUV output may be obtained. Conventional UV lasers are utilized as the upconverters for the ionized metals.