At&t Bell Laboratories

Bell Telephone Laboratories

Jonathan C White

John E Bjorkholm

Richard R Freeman

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.

Tunable indium UV anti-Stokes Raman laser

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.

Pulsed plasma generation of extreme ultraviolet radiation

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.

Anti-Stokes Raman upconverter for CO.sub.2 lasers

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.

Stimulated anti-Stokes Raman up-converter

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.

Bromine anti-stokes raman laser

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.

Tunable anti-Stokes Raman laser

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.

Auto-ionization pumped anti-Stokes Raman laser

An atomic or molecular beam detector is disclosed wherein the beam to be detected is coupled through a chopper to form a spatially modulated beam which is then directed at the pressure sensitive surface of a small sensitive microphone. The electrical output signal of this microphone is coupled to a phase-sensitive detector in order to detect the energy that is present in the signal at the frequency corresponding to the chopping rate. In the specific embodiment disclosed, a light beam is also coupled through the chopper in order to develop a second electrical signal which is mixed with the electrical output of the microphone and then coupled through a low pass filter to provide a DC signal when the atomic or molecular beam is present.

Universal detector for atomic and molecular beams

A laser apparatus for inverting a population in an atomic or molecular species is provided. Energy is stored in a first species and a laser induced collisional energy transfer from that first species to a selected dissociative molecular state of a second species causes an inversion of one of the constituents of the second species. This is represented, in one embodiment of the present invention which utilizes a second species comprising a diatomic molecule, by the reaction

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Lincroft, NJ, United States of America

Jonathan C White