Abstract: The 1.06.mu. Nd transition in a co-doped Cr,Nd:Gd.sub.3 Sc.sub.2 Ga.sub.3 sub.12 (Cr,Nd:GSGG) gain element is obtained by diode pumping Cr.sup.3+ at 670 nm and produces efficient, low threshold laser operation. Although co-doped Cr,Nd:GSGG was developed for more efficient flashlamp pumping, it has the desirable property of having an extraordinarily broad absorption to allow for efficient diode pumping relative to the Nd:YAG laser. The consequent broad bandwidth tolerance of the Cr,Nd:GSGG for the diode pumping radiation allows diode pumping of the 1.06.mu. transition without regard to the wavelength of the visible diodes which has the potential for reducing the cost of the semiconductor pump and also demonstrates the extended versatility of these diodes which previously had been restricted to pump the Cr.sup.3+ tunable vibronic lasers. CW and long pulse diode pumping provided pump power levels as high as 300 mW cw and 1 W pulsed. The lowest threshold power was measured at 938 .mu.

Abstract: A multiple gain-element ring laser has the capability of being scaled to her CW or pulsed output powers. Optical pumping is accommodated in a plurality of optically interconnected single gain-element "building blocks", each made up of a mirror associated with a gain element, such as Nd:YAG or Nd:YVO.sub.4, pumped by the optical pumping light from, for example, separate diodes in a focus (waist) at or near an exterior face of each gain element. A resonator mode is established in each gain element which also comes to a focus (waist) at or near the same exterior face in each gain element of the multi-element ring laser. Concatenating the gain elements and the associated mirrors into a desired multiple gain-element ring laser configuration provides for good overlap between the pump light from the several diodes and the resonator mode to achieve desired power levels at an improved efficiency. inclusion of a Q-switch and/or mode locker provides Q-switched and/or mode locked operation.

Abstract: A technique and apparatus employs a plurality of laser pumping emissions fed as collimated parallel beams from a multi-faceted reflective solid with highly reflective faces into a single aperture lens to concentrate all the laser pumping emissions onto a spot on the face of the laser crystal for the responsive longitudinal pumping thereof.

Abstract: A diode pumped ring laser allows for the combination of more pumping mode diation from pumping laser diodes for pumping at least one gain element which is simultaneously end pumped in two longitudinal resonator axes that intersect in a focused waist at a bounce point. Each gain element and associated mirrors are disposed to direct a hemispherical shaped resonator mode to a focus (waist) in each gain element where the resonator mode is reflected from the waist and diverges away to thereby form two cone-shaped active volumes in each gain element. Locating and orienting pumping diodes to longitudinally end pump the resonator modes with their pumping radiation to have a nearly perfect overlap of the resonator mode throughout the length of the active volumes in each gain element assures a more efficient, higher power end pumping of the gain elements. Appropriately arranging gain elements and mirrors directs pumping mode radiation to enter an exterior face and leave through an interior face of each gain element.

Abstract: A low threshold resonator for an alexandrite laser receives a 680 nm pumping beam from at least one laser pump to provide alexandrite laser emission at around 751 nm. An alexandrite crystal or rod receives the 680 nm beam and has an exterior face provided with a dichroic coating highly transmissive to the 680 nm beam and highly reflective to the 751 nm emission and has an interior face provided with an AR coating antireflective to the 751 nm emission. A mirror, provided with a HR coating that is highly reflective to the 751 nm emission, has an appropriate radius of curvature and is appropriately spaced from the exterior face of the alexandrite rod to focus reflected 751 nm emission in a resonator mode on the exterior face of the alexandrite rod to assure low threshold pumping thereof. The mirror has a radius of curvature which is the same as the spacing between the exterior face of the alexandrite rod and the mirror to focus the reflected emission in the resonator mode in a spot size on the exterior face.