Abstract: The present invention provides electroluminescent materials that emit very bright light with little energy consumption, little loss of energy converted into heat, etc., and suffers from little deterioration due to long-term use, in particular, inorganic electroluminescent materials that emit blue to green light having a wavelength shorter than yellow.

Abstract: The present invention provides electroluminescent materials that emit very bright light with little energy consumption, little loss of energy converted into heat, etc., and suffers from little deterioration due to long-term use, in particular, inorganic electroluminescent materials that emit blue to green light having a wavelength shorter than yellow.

Abstract: A transition metal doped spinel type MgAl2O4 fluorescent material capable of laser oscillation and a laser apparatus using the same. It is made from a mixed raw material of an Al raw material and a Mg raw material added thereto in an amount together with a transition metal raw material so that the amount of Mg exceeds that of Al by a few percents in terms of molar ratio, by shaping the mixed raw material under pressure to form a source material rod, and single-crystallizing the source material rod in a selected gaseous atmosphere by floating zone melting. The doping amount of Ti is such that in composition formula MgAl2-xTixO4 it lies in a range: 0.003?x?0.01. The doping amount of Mn is such that in composition formula Mg1-xMnxAlO4 it lies in a range: 0.003?x?0.01.

Abstract: The nonlinear optical element includes a sunstrate and one or more transparent microspheres made of a nonlinear optical active substance system fixed to the substrate, or the nonlinear optical element includes one or more transparent microspheres contacting a solid medium and fixed to the substrate. The element can be used for controlling nonlinear optical characteristics such as light amplification, optical switching, injection mode locking, and coupling of whispering gallery modes.

Abstract: An optical control system and method comprised of obtaining optical bistability by radiating a crystal with both the exciton energy level and the excitonic molecule energy level as the optical excition energy level, with a laser beam having energy less than (Em/2-.gamma.), in which Em is the excitonic molecular energy level, an .gamma. is the half-amplitude level of absorption spectrum of two-photon resonance. The advantage of optical bistability is that high speed switching of an order of pico-seconds is possible due to the coherent non-linear response, and that switch-on and switch-off energy required is less than pico-Joule.

Abstract: Optical recording media for storing information on which bits are formed by applying radiant energy to a polydiacetylene thin film supported by a substrate, so that the main chain structure of the polydiacetylene is transformed into another form or forms. The optical recording media has the advantages of allowing high-speed recording both with small amounts of energy for recording and with high recording density.