A folded slab waveguide laser having a hybrid waveguide-unstable resonator cavity. Multiple slab waveguides of thickness t supporting vertical waveguide modes are physically arranged above one another in a stack and optically arranged in series through one or more cavity folding assemblies with curved mirrors. A gain medium such as a gas is arranged in each slab. Each cavity folding assembly is designed to redirect the radiation beam emitted from one slab waveguide into the next waveguide and also at the same time to provide a focus for the radiation beam so that a selected vertical waveguide mode (or modes) is (or are) coupled efficiently into the next slab.

A folded slab waveguide laser having a hybrid waveguide-unstable resonator cavity. Multiple slab waveguides of thickness t supporting vertical waveguide modes are physically arranged above one another in a stack and optically arranged in series through one or more cavity folding assemblies with curved mirrors. A gain medium such as a gas is arranged in each slab. Each cavity folding assembly is designed to redirect the radiation beam emitted from one slab waveguide into the next waveguide and also at the same time to provide a focus for the radiation beam so that a selected vertical waveguide mode (or modes) is (or are) coupled efficiently into the next slab.

The present invention relates an apparatus and method for measuring range-resolved atmospheric sodium temperature profiles using a space-based Lidar instrument, including a diode-pumped Q-switched self-Raman c-cut Nd:YVO.sub.4 laser with intra-cavity frequency doubling that could produce multi-watt 589 nm wavelength output. The c-cut Nd:YVO.sub.4 laser has a fundamental wavelength that is tunable from 1063-1067 nm. A continuous wave narrow linewidth diode laser is used as an injection seeder to provide single-frequency grating tunable output around 1066 nm. The injection-seeded self-Raman shifted Nd:VO.sub.4 laser is tuned across the sodium vapor D.sub.2 line at 589 nm. In one embodiment, a space-qualified frequency-doubled 9 Watt at 532 nm wavelength Nd:YVO.sub.4 laser, is utilized with a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.

The present disclosure relates, generally, to lasers and, more particularly, to lasers with a setback aperture. In one in illustrative embodiment, a laser comprises front and rear resonator mirrors, an output window positioned near the front resonator mirror, and a plurality of waveguide walls extending between the front and rear resonator mirrors and extending between the rear resonator mirror and an aperture defined by the plurality of waveguide walls, such that a laser beam formed between the front and rear resonator mirrors will propagate in free-space between the aperture and the output window so that a first cross-sectional profile of the laser beam at the aperture will be different than a second cross-sectional profile of the laser beam at the output window.

A frequency-doubled laser, including: a first reflecting mirror, a second reflecting mirror, a gain medium, a telescope module, a polarizing element, and a nonlinear crystal; the first reflecting mirror and the second reflecting mirror are spaced apart to form a resonator of the frequency-doubled laser; the polarizing element, the gain medium, the telescope module, and the nonlinear crystal are located in the resonator, and the telescope module is located between the gain medium and the nonlinear crystal. The present disclosure further provides a method of generating harmonic laser. The frequency-doubled laser and the method of generating harmonic laser make the position of nonlinear crystal more flexible, and the possibility of damage to the nonlinear crystal is reduced.

A compact laser is provided for in accordance with an exemplary embodiment in the present disclosure includes a compact resonator structure using a non-planar geometry of bulk components. The laser includes a preferred rotational direction of lasing modes and employs bulk components for establishing the preferred rotational direction of lasing modes within resonator. In some embodiments, the preferred rotational direction of lasing modes is established using a reflective element that is outside the resonator structure. In some embodiments, the reflective element induces polarization shifts in the reflected light that are compensated for by a wave plate, which may be outside the resonator structure.

A multi-stage optical amplifier has an input port for receiving an optical signal and a relatively short erbium doped optical fiber is coupled to the input port. Complex costly pump feedback is not required as a constant non-varying saturation pump is configured to provide non varying output power pump light of a predetermined wavelength suitable for excitation and full saturation of the erbium ions such that a full population inversion occurs. The length of the short erbium doped fiber and rare earth doping concentration of the erbium doped fiber is such that when pumped by said pump provides amplification of the optical signal of less than 15 dB. Locating a gain flattening filter after the short erbium doped optical fiber provides a relatively flat amplified output signal. Multi-stages of similar short erbium doped fibers pumped and saturated by the same pump signal economically provide increased amplification of the signal and filters after each state flatten the gain.

A multi-stage optical amplifier has an input port for receiving an optical signal and a relatively short erbium doped optical fiber is coupled to the input port. Complex costly pump feedback is not required as a constant non-varying saturation pump is configured to provide non varying output power pump light of a predetermined wavelength suitable for excitation and full saturation of the erbium ions such that a full population inversion occurs. The length of the short erbium doped fiber and rare earth doping concentration of the erbium doped fiber is such that when pumped by said pump provides amplification of the optical signal of less than 15 dB. Locating a gain flattening filter after the short erbium doped optical fiber provides a relatively flat amplified output signal. Multi-stages of similar short erbium doped fibers pumped and saturated by the same pump signal economically provide increased amplification of the signal and filters after each state flatten the gain.

An erbium doped block of glass has input port and reflective end faces arranged such that a signal is launched into the block and is amplified as it traverses the block following a zig-zag path. A laser diode pump is focused to excite erbium ions within the block thereby amplifying the input signal light traversing the block numerous times. A gain flattening filter flattens the gain of the signal being amplified numerous times as the filter is within the path upon each pass across the block.

The invention relates to a discoidal or cuboidal solid body for a laser amplification system of a solid-state laser, which solid body contains at least one laser-active material, has an upper side defining an upper side plane and a lower side defining a lower side plane, wherein the upper side plane and the lower side plane are inclined in relation to each other and enclose an angle of inclination, wherein the lower side is provided with a first reflective coating, wherein the upper side is provided with a second reflective coating, and wherein at least one of the upper side and the lower side has at least one optical input coupling opening for input coupling at least one of a seed laser radiation field and a pump laser radiation field into the solid body between the first and the second reflective coating.