A new optically pumped far infrared (FIR) laser with separate pump beam reflector and FIR output coupler is developed. The configuration of the new FIR laser greatly simplifies the tuning of the laser and enables the optimization of the pump beam absorption without affecting the laser alignment.

A microwave excited gas slab laser comprising a waveguide wherein the electrodes are covered with multi-layered stripes either forming a photonic band-gap or having a refractive index lower than 1.

A laser apparatus is provided, comprising a semiconductor substrate, an active layer disposed on the semiconductor substrate, a folded waveguide disposed on the active layer and forming a resonant structure, the folded waveguide comprising at least two substantially straight waveguide portions coupled by a connecting waveguide structure, with the folded waveguide having a first end and a second end located at one or more edges of the semiconductor substrate, wherein at least one of the ends includes a mirror, and an electrode coupled to the folded waveguide and configured to create photons in the folded waveguide when receiving electrical power. The waveguide emits laser light comprising the photons, with the laser light emitted at an edge of the semiconductor substrate.

III-V lasers integrated with silicon photonic circuits and methods for making the same include a three-layer semiconductor stack formed from III-V semiconductors on a substrate, where a middle layer has a lower bandgap than a top layer and a bottom layer; a mirror region monolithically formed at a first end of the stack, configured to reflect emitted light in the direction of the stack; and a waveguide region monolithically formed at a second end of the stack, configured to transmit emitted light.

III-V lasers integrated with silicon photonic circuits and methods for making the same include a three-layer semiconductor stack formed from III-V semiconductors on a substrate, where a middle layer has a lower bandgap than a top layer and a bottom layer; a mirror region monolithically formed at a first end of the stack, configured to reflect emitted light in the direction of the stack; and a waveguide region monolithically formed at a second end of the stack, configured to transmit emitted light.

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.

A CO.sub.2 laser that generates laser-radiation in just one emission band of a CO.sub.2 gas-mixture has resonator mirrors that form an unstable resonator and at least one spectrally-selective element located on the optical axis of the resonator. The spectrally-selective element may be in the form of one or more protruding or recessed surfaces. Spectral-selectivity is enhanced by forming a stable resonator along the optical axis that includes the spectrally-selective element. The CO.sub.2 laser is tunable between emission bands by translating the spectrally-selective element along the optical axis.

In a laser oscillator, a pair of electrodes is disposed in a housing into which a gas is sealed, a waveguide is formed by the pair of electrodes, and a laser beam is configured to be extracted from an end of the housing. The laser oscillator includes a mirror holder attached to an end of the electrode, the end serving as an end of the waveguide, and a reflection mirror attached to the mirror holder and reflecting a laser beam generated in the waveguide. In the laser oscillator, a passage through which a cooling medium is passed is formed inside each of the pair of electrodes.

A resonator for a laser includes a first resonator wall and a second resonator wall with a lasing medium disposed in a gap therebetween. The resonator further includes a first mirror disposed at a first end of the first and second resonator walls and a second mirror disposed at a second end of the first and second resonator walls. The mirrors cooperate to form an intra-cavity laser beam that travels along a plurality of paths through the lasing medium. Furthermore, the first mirror and the second mirror form a laser resonator for a parasitic laser mode. A parasitic mode suppressor is located within the superfluous region.

A radio frequency, RF, slab laser comprising a live electrode (102) and a ground electrode (108) whose inwardly facing surfaces face each other to form a gap for forming a plasma discharge when the live electrode is supplied with a suitable RF drive signal. The electrodes are enclosed in a vacuum space by a vacuum housing (114) with an access aperture (116). The access aperture is sealed with a vacuum flange (70) that comprises an electrically insulating connector. A plurality of hollow conductors (62) are arranged to extend through the vacuum flange into the vacuum space and connect with the live electrode. The hollow conductors connect to the live electrode to supply it with its RF drive signal and also coolant fluid which is distributed through fluid circulation channels (80a, 80b). Coolant fluid is supplied to the live electrode through certain ones of the hollow conductors and taken out by others.