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 tunable laser has a first mirror, a second mirror, a gain medium, and a directional coupler. The first mirror and the second mirror form an optical resonator. The gain medium and the directional coupler are, at least partially, in an optical path of the optical resonator. The first mirror and the second mirror comprise binary super gratings. Both the first mirror and the second mirror have high reflectivity. The directional coupler provides an output coupler for the tunable laser.

An improved dental laser system has been developed to cut enamel quickly and precisely, without detrimental residual energy, to provide a replacement for conventional high speed rotary burrs and commercially available dental laser systems.

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 polarisation and mode selection technique for a gas waveguide laser is described in which a surface of the waveguide is formed to be substantially dielectric with a localised metallic region therein. The metallic region provides linear polarisation while the dielectric surface provides for low order mode selection. Embodiments are described to channel and planar waveguides with various resonator configurations. Ranges are provided for the size and location of the metallic region on the waveguide surface.

A radio-frequency, RF, slab laser 10 with a Z-fold resonator cavity defined by an output mirror 32, a first fold mirror 34, a second fold mirror 36 and a rear mirror 30. The second fold mirror 36 is rotated by an adjustment angle away from the angle it would have if the mirrors were all plane mirrors and directed the round trip beam path by direct reflection. Moreover, the rear mirror 30 is rotated by an adjustment angle that is approximately twice the adjustment angle of the second fold mirror 36. These rotations of the rear mirror 30 and second fold mirror 36 suppresses parasitic mode paths that would otherwise exist.

A system and a method for generating tunable ultrafast optical pulses, the method comprising spectral broadening of a laser input beam by propagating the laser input beam in a nonlinear medium of a third-order nonlinear susceptibility .sup.(3), yielding an output laser spectrum; and one of: i) selecting at least one portion of the output laser spectrum, yielding an output pulse different than the input pulse and centered at a different frequency; ii) temporal compensation and spatial spreading of spectral components of the output laser spectrum; selecting two pulses at two different frequencies; and nonlinearly mixing the two pulses together in a first second-order nonlinear susceptibility .sup.(2) nonlinear crystal into a third pulse centered at a frequency which is a difference between the frequencies of the first two pulses; and iii) dividing output laser spectrum into a pump beam and a probe beam, directing a pump pulse to a third second-order nonlinear crystal for THz radiation generation; and directing a probe pulse to a third second-order nonlinear crystal for THz radiation reconstruction.

A carbon dioxide gas-discharge slab-laser is assembled in a laser-housing. The laser-housing is formed from a hollow extrusion. An interior surface of the extrusion provides a ground electrode of the laser. Another live electrode is located within the extrusion, electrically insulated from and parallel to the ground electrode, forming a discharge-gap of the slab-laser. The electrodes are spaced apart by parallel ceramic strips. Neither the extrusion, nor the live electrode, include fluid coolant channels. The laser-housing is cooled by fluid-cooled plates attached to the outside thereof.

An optical element includes an optical waveguide layer. The optical waveguide includes a periodic structure of grooves. The optical waveguide layer has a layer-thickness equal to or greater than 1.5 m and is made of material selected from a group consisting of Ta2O5, Al2O3, LiNbO3, LiTaO3, AlN, GaN, SiC, and Yttrium aluminum garnet (YAG). (D/0.5)2.5 is satisfied where D indicates the depth of groove; and indicates the pitch of the arranged grooves in the periodic structure. The unit of is identical to the unit of D.

A waveguide gas laser having a laser resonator cavity of a variable length is subjected to cyclical varying of the length of the cavity during generation of a laser beam a length variation amount sufficient to force a laser beam generated in the resonator cavity though a substantially complete optical longitudinal cavity mode at a rate operable to smooth at least one laser beam parameter variation. In this manner variation in the laser beam parameter is averaged by moving through at least a portion of an optical longitudinal cavity mode.