Abstract: A novel superlattice quantum cascade (SLQC) laser has undoped SL active regions, with the dopant concentration in the injector region being selected, such that, under an appropriate electrical bias, the SL active region is substantially electric field free. The absence of dopant atoms in the SL active region results in reduced carrier scattering and reduced optical losses, with consequent low threshold current and/or room temperature operation. The novel laser emits in the mid-IR spectral region and can be advantageously used in measurement or monitoring systems, e.g., in pollution monitoring systems.

Abstract: A surface emitting semiconductor laser of a ring cavity type with a small cavity loss includes a ring cavity or resonator which is constructed wituout using at least one of a pair of special high-reflection multi-layer mirrors and formed in a plane approximately perpendicular to its substrate. The ring cavity is built by a parallel face parallel to the substrate and at least one total reflection face formed opposed to the parallel face. The total reflection face may be a mesa-shaped semiconductor face, a polygonal cone-shaped semiconductor face, a quadrangular cone-shaped semiconductor, a circular cone-shaped semiconductor face or the like.

Abstract: A high efficiency, narrow spectral linewidth lasing pixel device that implements a low-voltage spatially patterned variable loss element placed inside an optically pumped high-gain laser cavity is disclosed. The output properties of this system make it useful for digital projection displays.

Abstract: A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals.