A laser system for generating a series of laser pulses comprising a laser generator that supplies an injection pulse to an amplifier; said amplifier comprising: a gain medium enclosed between a first mirror and a second, output, mirror opposite to said first mirror; and an optical switch set in the proximity of said first mirror; said laser system being characterized in that said amplifier is an unstable laser resonator and said injection pulse is supplied to said laser resonator in synchronism with opening of said optical switch; said series of laser pulses comprises at least one pulse having a duration shorter than or equal to 2 ns and an energy higher than 100 mJ and at least three times higher than the energy of any other pulse of said series of pulses.

A laser source includes an optical resonator including first and second reflectors having first and second reflection spectral bands. A gain medium is disposed in the optical resonator. The gain medium has a gain spectrum. Center wavelengths of at least two of: the first reflection spectral band; the second reflection spectral band; or the gain spectrum are offset relative to each other for reduction of a spectral variance of the laser source. For example, the first and the second reflection spectral bands may be offset relative to one another to form an overlap area above a lasing threshold. The lasing is limited to the overlap area. When the overlap area accommodates a single lasing mode, the output emission of the laser source is monochromatic.

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.

A method and apparatus for characterizing an optical element. The optical element is part of a laser and is mounted on a translation stage to scan the optical element transverse to an intracavity laser beam. A performance characteristic of the laser is recorded as a function of position of the optical element.

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.

Gaseous laser systems and related techniques are disclosed. Techniques disclosed herein may be utilized, in accordance with some embodiments, in providing a gaseous laser system with a configuration that provides (A) pump illumination with distinct edge surfaces for an extended depth and (B) an output beam illumination from a resonator cavity with distinct edges in its reflectivity profile, thereby providing (C) pump beam and resonator beam illumination on a volume so that the distinct edge surfaces of its pump and resonator beam illumination are shared-edge surfaces with (D) further edge surfaces of the amplifier volume at the surfaces illuminated directly by the pump or resonator beams, as defined by optical windows and (optionally) by one or more flowing gas curtains depleted of the alkali vapor flowing along those optical windows. Techniques disclosed herein may be implemented, for example, in a diode-pumped alkali laser (DPAL) system, in accordance with some embodiments.

The present invention relates to a laser system and a method of generating a defined spatial mode-shaped laser beam using an unstable laser resonator layout. The laser system for mode shaping of a laser beam within an unstable optical resonator layout comprising an active medium, characterized in that, the active media comprises a pumped area, wherein the gain distribution is generated by an optical pump beam's spatially intensity profile. In a preferred embodiment, the system may further comprise an end-pumped layout to deliver the spatially shaped optical pump beam to the active medium; and/or an active element and/or a passive element for modifying the resonator losses; and/or means of output coupling of a laser beam from said unstable resonator layout. The system according to the present invention is suitable to deliver a top-hat beam profile.

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 MOPA laser system that includes a seed laser configured to output pulsed laser light, an amplifier configured to receive and amplify the pulsed laser light emitted by the seed laser; and a pump laser configured to deliver a pump laser beam to both the seed laser and the amplifier and a variable attenuator configured to eliminate missing Q-switched pulses.

A MOPA laser system that includes a seed laser configured to output pulsed laser light, an amplifier configured to receive and amplify the pulsed laser light emitted by the seed laser; and a pump laser configured to deliver a pump laser beam to both the seed laser and the amplifier.