The invention relates to a resonator mirror (4) for an optical resonator (1) of a laser device (2), especially of a gas laser or a slab waveguide laser, comprising a reflective surface (6) with a structured area (5) which spans across a region of the reflective surface (6) centered about the optical axis (5). According to one variant of the principle underlying the invention, the structured area (5) has at least one reflective surface cross-section (8, 18, 28, 38, 48, 58, 68) which is offset with respect to the reflective surface (6) outside the structured area (5) and parallel to the optical axis (A) by half of a predefined wavelength or by a whole multiple of half the predefined wavelength. According to another variant, the structured area (5) has at least two surface cross-sections (8, 18, 28, 38, 48, 58, 68) which are offset against each other and parallel to the optical axis (A) by half of a predefined wavelength or by a whole multiple of half the predefined wavelength. In addition, the invention relates to a laser device (2) whose optical resonator (1) comprises a resonator mirror (4) designed in such a manner.

A dual-comb measuring system is provided. The dual comb measuring system may include a bi-directional mode-locked femtosecond laser, a high-speed rotation stage, and a fiber coupler. The high-speed rotation stage may be coupled to a pump diode.

A method and a system for measurement of high laser field intensity, the method comprising tight focusing a non-Gaussian azimuthally polarized laser mode beam to a focusing spot, measuring a spectral line shape of a selected ionization state induced by a longitudinal oscillating magnetic field created by the tight focusing in the focusing spot; and determining the laser intensity from the spectral line shape. The system comprises a laser source of a peak power in a range between 100 terawatt and 10 petawatt; a converter unit; a tight focusing optics; and spectral measurement means; wherein the converter unit polarizes a main laser beam from the laser source into a non-Gaussian azimuthally polarized laser mode beam; the tight focusing optics focuses the azimuthally polarized laser mode beam to a focusing spot, yielding a longitudinal oscillating magnetic field of an intensity proportional to the laser intensity, the spectral measurement means measuring a line shape of a selected ionization state induced by the longitudinal oscillating magnetic field in focusing spot.

A passively, Q-switched laser operating at an eye safe wavelength of between 1.2 and 1.4 microns is described. The laser may operate at a lasing wavelength of 1.34 microns and use a gain element of Nd:YVO.sub.4 and a saturable absorber element of V:YAG. The position of the resonator axial mode spectrum relative to a gain peak of the gain element is controlled to yield desired characteristics in the laser output.

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.

An optical element may include a plurality of subsurface induced scattering centers formed in the optical element, where the plurality of subsurface induced scattering centers scatter light passing through the optical element. In some implementations, the plurality of subsurface induced scattering centers may form a scattering region in the optical element. Additionally, or alternatively, the plurality of subsurface induced scattering centers may spatially vary transmission of light through the optical element. The optical element may be an optical waveguide, a bulk optic, and/or the like.

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.

Examples described herein relate to an optical device. The optical device includes a first microring resonator (MRR) laser having a first resonant frequency and a first free spectral range (FSR). The first FSR is greater than a channel spacing of the optical device. Further, the optical device includes a first frequency-dependent filter formed along a portion of the first MRR laser via a common bus waveguide to attenuate one or more frequencies different from the first resonant frequency. A length of the common bus waveguide is chosen to achieve a second FSR of the common bus waveguide to be substantially equal to the channel spacing to enable a single-mode operation for the optical device. Moreover, the optical device includes a first reflector formed at a first end of the common bus waveguide to enhance a unidirectionality of optical signal within the first MRR laser.

Disclosed is an injected laser including an optical amplifying medium arranged inside a triggered laser cavity, the optical amplifying medium having a spectral amplifying band. The injected laser includes an optical phase-modulation device, arranged between the injection source and the laser cavity, the optical phase-modulation device being configured to periodically modulate as a function of time a phase of the monochromatic continuous laser radiation at a modulation frequency equal to a natural integer multiple of the free spectral range of the laser cavity, so that the phase-modulated injection source generates a polychromatic injection radiation.

External cavity laser systems are described that can operate with essentially no mode hopping. One example configuration of the laser system includes a semiconductor laser device, a folded cavity external to the semiconductor laser device, where at the semiconductor laser device is positioned at a fold in the folded cavity. In this configuration, at least one mirror is positioned in the folded cavity to enable sustained propagation of light within the folded cavity, and at least two polarization elements are positioned in the folded external cavity. The polarization elements cause a polarization state of the light that impinges in different directions on each semiconductor laser device that is positioned at a fold to be orthogonal to one another, thus eliminating or substantially reducing mode hopping in the laser output.