Abstract: A glass fiber laser system includes a laser resonator cavity having a resonant path and an erbium-doped glass fiber lasing element with an output of from about 1.5 to about 1.6 micrometers within the laser resonator cavity. A light source directed into an input end of the glass fiber lasing element optically pumps the lasing element to emit light. A passive Q-switch lies along the resonant path within the laser resonator cavity. The Q-switch is formed of a host material having a concentration of uranium ions therein, so as to be a saturable absorber of the light emitted by the lasing element. The Q-switch is preferably a uranium-doped fluoride crystal such as U:CaF.sub.2, U:SrF.sub.2, or U:BaF.sub.2.

Abstract: A laser system includes a laser resonator cavity having a resonant axis and an Er:glass, Er:YAG, or other lasing element with an output of from about 1.4 to about 1.65 micrometers within the laser resonator cavity. A flash lamp optically pumps the lasing element to emit light. A Q-switch crystal lies along the resonant axis within the laser resonator cavity. The Q-switch crystal is formed of a host material having a concentration of U.sup.2+ ions therein, so as to be a saturable absorber of the light emitted by the lasing element. The Q-switch crystal is preferably a U.sup.2+ -doped fluoride such as U:CaF.sub.2, U:SrF.sub.2, or U:BaF.sub.2.

Abstract: A single focus backward Raman laser that is a compact, efficient apparatus for converting light at a first wavelength provided by a pump laser to light at a Raman-shifted wavelength. The laser is comprised of a gas cell, two lenses, a feedback mirror, an optical isolator, and a dichroic mirror, and the gas cell contains a Raman gas medium. The Raman gas medium may be methane, hydrogen, or deuterium, for example. The two lenses bring the pump and Raman light to a single focus in the gas cell and also recollimate the light after it exits the cell. The optical isolator is used to prevent the backward-scattered pump light from reentering the pump laser. The dichroic mirror is used to reflect out the backward-scattered Raman light, while transmitting the pump laser light. The present laser has a much improved beam divergence and is much less sensitive to optical misalignments than conventional Raman half-resonator designs.

Abstract: Intracavity Raman lasers comprising a pump resonator and a Raman resonator that eliminates alignment problems associated with multi-mirror intracavity lasers. The pump resonators include a laser rod and a pump source. In one embodiment, a first retroreflector is disposed at one end of the pump resonator, and an output mirror is disposed at an opposite end thereof. A Q-switch, a dichroic mirror, and a prism are disposed between the laser rod and the output mirror. The pump resonator radiates pump energy at a first wavelength (1.06 .mu.m) between the first retroreflector and the output mirror. The Raman resonator includes a Raman gas cell having first and second lenses disposed on opposite ends thereof for focusing laser energy into the Raman cell, and a second retroreflector that forms one end of the Raman resonator. The output mirror forms an opposite end of the cell, and the dichroic mirror and the prism are disposed between the second retroreflector and the first lens.

Abstract: A Raman laser apparatus for producing a high energy output beam with low divergence. An optical pump beam (14) propagates through first and second focuses (34,36) inside a cell containing a gaseous Raman medium (20) at a pressure selected to promote stimulated Raman scattering (SRS) and suppress stimulated Brillouin scattering (SBS). The pump beam (14) generates a backward SRS wave at the second focus (36), which propagates back through the first focus (34) and acts as a seed for backward SRS therein. The backward SRS wave is amplified at the first focus (34), and extracted therefrom as an output beam (38) by output means (40). Any forward SRS wave which is generated at either the first focus (34) or the second focus (36) may be reflected back through the second focus (36) and then through the first focus (34) to further increase the backward SRS seed beam at the first focus. The output beam (38) is retro-reflected, and has beam divergence comparable to the pump beam divergence.

Abstract: A cavity which is resonant at a laser pumping frequency is defined by a reflective surface (92) and a mirror (110). A Raman medium (106) is contained within the cavity, as is a laser (90). A Q-switch (94), when not spoiling the Q of the cavity, allows photon density to increase within the cavity. When the Raman threshold of the Raman medium is exceeded, the Raman medium absorbs and then radiates photons. The radiated photons are at longer wavelength than the laser photons, and also occur in very short (less than ten nanoseconds) pulses. The radiated photons are reflected by a mirror (101) and exit the cavity through one of the reflectors defining the cavity (mirror 110). The invention shifts the wavelength and shortens the pulse duration of pulses produced by the laser (90).

Abstract: A lasing medium (3) and a Raman medium (20) share a common optical cavity. The lasing medium (3) projects laser light into the Raman medium (20) and, when a threshold intensity within the Raman medium is reached, the Raman medium absorbs the laser light and re-radiates coherent light at a shifted frequency. Optical elements within the system provide an optical cavity for the lasing medium and a second cavity for the Raman medium.