Abstract: Noble crystal of 4-dimethylamino-4-stilbazolium tosylate (DAST) useful as an electro-optical element. A DAST crystal having a size effective for use as an electro-optical element is provided by a twin crystal of DAST. The twin crystal of DAST can be obtained according to a seed crystallization method or a slope crystal growing method.

Abstract: An organic electroluminescent device including a pair of electrodes and a layer that is disposed between the pair of electrodes and includes a compound represented by the following formula (1): wherein each of A1, A2, B, C, n1 and n2 is given the definition as set forth in the specification and claims.

Abstract: Noble crystal of 4-dimethylamino-4-stilbazolium tosylate (DAST) useful as an electro-optical element. A DAST crystal having a size effective for use as an electro-optical element is provided by a twin crystal of DAST. The twin crystal of DAST can be obtained according to a seed crystallization method or a slope crystal growing method.

Abstract: An organic electroluminescent device including a pair of electrodes and a layer that is disposed between the pair of electrodes and includes a compound represented by the following formula (1): wherein each of A1, A2, B, C, n1 and n2 is given the definition as set forth in the specification and claims.

Abstract: A method for producing an organic crystal is disclosed. One embodiment comprises maintaining a capillary tube containing a fused liquid of an organic crystal material and having a fused liquid reservoir at one end thereof at a temperature not less than the fusion point of the organic crystal material together with the fused liquid reservoir, reducing the temperature of the fused liquid in the fused liquid reservoir to precipitate seed crystals, and then slowly cooling the capillary tube successively from the end toward the other end to allow a single crystal to grow from the seed crystal in the capillary tube. Because of the large quantity of the fused liquid, a seed crystal can be formed and allowed to grow even from a fused liquid of an organic crystal material which hardly crystallizes in the form of a fused liquid.

Abstract: A device for generating a second harmonic from a laser source is disclosed. The light from the laser passes through an optical fiber in which the second harmonic is generated. The light exiting from the optical fiber has a conical wave surface which is incident upon a collimating lens. Because the collimating lens has a diffraction lattice formed thereon, it is easy and efficient to collimate the second harmonic. It is also possible to decrease the size of the apparatus due to the use of the diffraction lattice formed on the collimator lens. This enable such a device to be particularly useful with a small sized light source such as a semiconductor laser.

Abstract: An optical wavelength converter device of the optical fiber type comprises a core made of a nonlinear optical material and cladding of an amorphous material and surrounding the core, the cladding having a refractive index lower than the refractive index of the core. Another optical wavelength converter device comprises a two- or three-dimensional optical wavelength converter device produced by growing a nonlinear optical material crystal as an optical waveguide on or in an amorphous substrate having a refractive index lower than the refractive index of the nonlinear optical material crystal. Phase matching is achieved between a radiation mode of a wavelength-converted wave in the cladding or the substrate and a nonlinear polarized wave generated by a waveguide mode of first and second fundamental waves in the core or the optical waveguide.

Abstract: An optical wavelength conversion device is constituted by a pair of substrates disposed facing each other, and an optical waveguide formed of a nonlinear optical material and disposed between the substrates, thereby to convert a fundamental wave entering the optical wavelength conversion device formed to a second harmonic which is phase matched by Cherenkov radiation. At least one of the substrates is provided with a grating for entry of the fundamental wave, which is formed on a surface contacting the optical waveguide, and/or with a grating for radiation of the second harmonic, which is formed on a surface opposite to the surface contacting the optical waveguide. The optical wavelength conversion device is made by forming grooves on the substrates, filling a slight space between the substrates with a crystallizable organic nonlinear optical material, and gradually crystallizing the optical material.