The present invention provides a blue laser transmitter operating at the H-beta Fraunhofer line at 486.13 nm wavelength. The subject blue laser is based on pulsed lasing action in thulium doped into lutetium sesquioxide (Tm:Lu.sub.2O.sub.3). The laser wavelength is restricted by volume

Bragg grating to the vicinity of 1944 nm wavelength. The laser is operated with a q-switch to generate high-energy pulses within the nanosecond regime. The output at the 1944 nm wavelength is then frequency quadrupled in a single pass through non-linear crystals to a wavelength near the center of the H-beta Fraunhofer line. The operation at the 1944 nm wavelength in Tm:Lu.sub.2O.sub.3 is very efficient because this wavelength is located on a shoulder of a substantially broad emission peak at 1945 nm. In addition, at the 1944 nm wavelength, Tm:Lu.sub.2O.sub.3 has only a modest saturation fluence of about 15 J/cm.sup.2, which allows for efficient energy extraction.

Provided is a fixing device for a diffraction element including an element installation portion where a diffraction element is installed, and an element fixing portion that fixes the diffraction element installed on the element installation portion, wherein the element installation portion includes an element installation surface for curving the installed diffraction element in a discretionary shape, and the element installation surface is formed in an arch-like shape such that deformation of the diffraction element due to pressure of a cooling fluid is reduced.

Described herein are isolated ring cavities that have refractive and heat-generating components physically separated and mechanically held by flexure mounts that are adapted to function in combination with the physically separated structure to moderate the thermal expansion effects of the heat generated by the refractive and other heat-generating elements (e.g., gain element) of the optical cavity. The flexure mounts may be configured as thinned portions of connective elements, reducing the effects of thermal expansion of the baseplate and allowing a thermal isolation from the baseplate. Multiple flexure mounts may be arranged to minimize further the effects of thermal expansion of the baseplate.

Provided is a laser device in which: a laser medium doped with ytterbium emits light upon absorption of excitation light; the light emitted by the laser medium is amplified to obtain output light; and the output light is outputted in the form of a plurality of pulses. In the laser device, a spatial filter is disposed in the optical path of the light emitted by the laser medium or is disposed in the optical path of the output light outputted from an optical resonator, the spatial filter being configured to filter out a portion of the light or of the output light around the optical axis.

A single-frequency laser apparatus comprises a mirror and a volume Bragg grating (VBG) reflector defining a laser cavity therebetween and an optical gain material for emitting and amplifying an intra-cavity beam in the laser cavity. The optical gain material comprises a transition-metal doped crystal such as a crystal doped with transition-metal ions selected from one or more of Ti.sup.3+ ions, Cr.sup.2+ ions, Cr.sup.3+ ions or Cr.sup.4+ ions. A reflectivity spectrum of the VBG reflector and an optical length of the laser cavity are selected so that a beam output from the laser cavity is a single-frequency output beam and/or includes only one longitudinal mode of the laser cavity. The laser apparatus may provide a robust, compact, low cost, high-power wavelength adjustable (from approximately 650 to 950 nm), narrow linewidth (<100 kHz), single frequency laser source which is suitable for a wide range of applications from laser sensing, spectroscopy, and high precision frequency metrology sectors.

A mid-infrared semiconductor saturable absorber mirror based on InAs/GaSb superlattice comprises a GaSb substrate with an anti-reflection film coated on the lower surface of the GaSb substrate; InAs/GaSb superlattice which has a specific structure and thickness and is arranged on the GaSb substrate; and Bragg reflection film which is arranged on the InAs/GaSb superlattice, wherein Bragg reflection film is composed of multiple pairs of ZnS and YbF.sub.3 film layers with a thickness of ¼ wavelength, and the YbF.sub.3 film layer is connected with the InAs/GaSb superlattice. The device not only has a mid-infrared working range with a broadband operation bandwidth, but also has the advantages of designable parameters, outstanding robustness, high damage threshold and the like, and sets a foundation for the development of mid-infrared ultrafast mode-locked lasers.

A cooling jacket that houses a cooling fluid is provided. The cooling jacket includes a fixing part to which an element to be cooled is fixed. Furthermore, an inflow port through which the cooling fluid flows into the cooling jacket and an outflow port through which the cooling fluid flows out of the cooling jacket are provided. Furthermore, a bar-shaped (columnar) member is provided as a mechanism that enhances heat conduction between the cooling fluid in the cooling jacket and the fixing part via a heat transfer member.

An improved architecture for optical waveguides as used in a diode-pumped alkali laser system is provided by using micro-channel-etched silicon or other metal in place of the more usual sapphire.

A laser system comprising a gain medium configured to amplify incident electromagnetic radiation and a nonlinear optical element configured to convert electromagnetic radiation amplified by the gain medium to a shorter wavelength. The laser system is configured to introduce mode competition and nonlinear effects such that the nonlinear optical element produces output electromagnetic radiation having a frequency spectrum comprising a first peak formed of a first group of frequencies and a second peak formed of a second group of frequencies. A trough separates the first and second peaks. The first and second peaks are the only dominant peaks in the frequency spectrum. The output electromagnetic radiation has a coherence curve comprising a contrast ratio of less than about 0.1 at an optical path difference that is within the inclusive range of about 1.5 mm to about 2.5 mm.

Passively Q-switched lasers and short wave infrared (SWIR) electro-optical systems including such lasers. A passively Q-switched laser may include a gain medium (GM) having a stimulated emission cross section σ.sub.SE, a saturable absorber (SA) having an absorption cross section (σ.sub.a) which is less than three times the σ.sub.SE of the GM, and an optical resonator within which the GM and the SA are positioned, the optical resonator comprising a high reflectivity mirror and an output coupler, wherein at least one of the high reflectivity mirror and the output coupler comprises a curved mirror, directing light within the optical resonator such that an effective cross-section of a laser mode within the SA (A.sub.SA) is smaller than a cross-section of a laser mode within a Rayleigh length of the pump (A.sub.GM).