Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 nm but also other infrared wavelengths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 &mgr;m but also other infrared wavelgths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: A long wavelength infrared laser system is disclosed where radiation from laser sources such as frequency-doubled Nd:YAG or a Cr:LiSAF is used to resonantly pump a gain medium consisting of a holmium-doped fluoride crystal having a high active ion concentration. The laser pump source has a pulse duration that may be short enough to gain switch a particular transition or long enough to allow end-pumping with high energy densities without damage. The gain material has an absorption approximately resonant with the pump source wavelength, and the dopant concentration is selected to maximize absorption strength for a given excitation. The output radiation from the laser system consists of one or more wavelengths including, in particular 3.9 nm but also other infrared wavelgths such as 1.4 &mgr;m, 2.9 &mgr;m and 3.4 &mgr;m., several of which may be produced simultaneousely from the same laser material through the mechanism of cascade transitions.

Abstract: A solid state laser whose medium is a strontium aluminum fluoride crystal doped with chromium. This laser medium has a wavelength tuning range centered around 850 nm and the laser gain is estimated to be a factor of 2-3 times higher than that of emerald and alexandrite lasers at room temperature.

Abstract: A high power, broadly wavelength-tunable laser is provided which comprises as the laser medium particular single crystals of chromium-doped beryllium aluminate (BeAl.sub.2 O.sub.4 :Cr.sup.3+) having the chrysoberyl structure, means for exciting the laser medium and tuning means. The laser may be operated over a broad temperature range from cryogenic temperatures to elevated temperatures. Elevated temperatures are preferred, however, since they result in higher laser gain. Emission is in a spectral range from red to infrared, and the laser is useful in the fields of defense, communications, isotope separation, photochemistry, etc.CROSS-REFERENCE TO PRIOR APPLICATIONThis application is a continuation-in-part of application Ser. No. 953,067, filed Oct. 20, 1978.

Abstract: Improvements in Praseodymium solid state YLF lasers operating in the blueeen spectral region at room temperature and providing short pulses useful for underwater communication and detection systems. A dye laser with a narrow spectral output matched to the absorption spectra of the solid state laser is provided as a laser pump. The Pr doped YLF crystal of the solid state laser is physically oriented so it can be longitudinally pumped by light polarized parallel to the c-axis of the crystal, and the solid state laser is equipped with special spectrally selective mirrors. The foregoing and other modifications of prior Pr solid state laser systems provide increased efficiency and power output.

Abstract: An optically pumped crystalline laser that includes a small single crystal section of a polygonal cylinder; the dimensions of the crystal section and the index of refraction of the crystal and the medium surrounding the crystal are such that there is formed a dielectric resonator that is totally reflective for a small number of modes. The material of which the crystal section is composed is one that is capable of being made optically thick in thin sections. The resonator is optically pumped and the lasing radiation therein is coupled to an optical element that is placed in close proximity thereto by virtue of an evanescent field that arises from the lasing action in the resonator.

Abstract: Methods and compositions for using an up-conversion phosphor as an emitting material in a reflective displays and Polymer compositions for display mediums, and blue green red (BRG) display mediums. Roles of the pumping duration and character on the temperature and the efficiency of the up-conversion process in (Ytterbium, Erbium or Thulium) co-doped fluoride crystals are set forth. Methods, compositions and display mediums for using up-conversion phosphors in both reflective and transmissive displays in which the substrate and pixel shapes are designed to maximally remove heat deposited in the emitting material and thereby improve the efficiency of up conversion.