Abstract: Method for obtaining an organic polycrystalline material having in particular electro-optical properties, said material obtained and an electro-optical modulator comprising said material. This method includes a stage (1) for preparing a powder having a size grading of 500 to 800 nm of an organic compound having a delocalized system of .pi. electrons and presenting a non-centrosymmetrical crystalline structure, as well as intramolecular load transfer groupings, a stage (2) for drying the powder under vacuum, a stage (3) for pre-pressing the powder under vacuum, and a hot stage (5) for the uniaxial compression of the dried powder under vacuum. This method enables polycrystalline materials to be obtained, said materials comprising elongated monocrystalline grains orientated according to a given direction.

Abstract: The process for the photochemical treatment of a solid material consists of exposing the latter to light pulses produced by at least one glow discharge elongated tube (4) having a rare gas under low pressure and whereof the gas, the pressure and the characteristics of the discharge are adapted to said material and its precursors, each pulse containing an extensive emission spectrum between 160 and 5000 nm. An electrical circuit with modulatable electrical characteristics (LC) makes it possible to modulate the discharge characteristics of the tube and the storage of the energy necessary for said discharge.

Abstract: Method for obtaining an organic polycrystalline material having in particular electro-optical properties, said material obtained and an electro-optical modulator comprising said material.This method includes a stage (1) for preparing a powder having a size grading of 500 to 800 nm of an organic compound having a delocalized system of electrons .pi. and presenting a non-centrosymmetrical crystalline structure, as well as intramolecular load transfer groupings, a stage (2) for drying the powder under vacuum, a stage (3) for pre-pressing the powder under vacuum, and a hot stage (5) for the uniaxial compression of the dried powder under vacuum.This method enables polycrystalline materials to be obtained, said materials comprising elongated monocrystalline grains orientated according to a given direction.

Abstract: Process for depositing and crystallizing a thin layer of organic material by means of a beam of energy.A compact block formed of organic material is disposed adjacent one of the faces of the substrate, the block is subjected through the substrate to the action of a laser beam, so as to desorb the organic material forming the block, the substrate being optically transparent to the beam, and a relative displacement is performed between the substrate and the beam in order to sweep such faces over a given path, to enable the desorbed material to be deposited on the face of the substrate opposite the block, and the material thus deposited to be crystallized in a quasi-crystalline form.Application to the manufacture of integrated optical products, such as lenses, mirrors, networks and the manufacture of opto-electronic components.