Abstract: An optical bistable photorefractive crystal device is provided in which a photorefractive crystal disposed between two mirrors is uniformly illuminated by a light beam, a signal beam being focused on a given portion of the crystal to cause bistable switching of this portion inside the crystal.

Abstract: A device for establishing optical connection links between electronic component cards forming part of a package. The device comprises a transparent plate having parallel faces and a light source which emits a divergent beam and is implanted on a first card. The beam is reflected from a first optical diffracting element in the form of a collimated beam which undergoes multiple reflections from alternate reflecting elements to a second optical diffracting element and is converted by the second element to a convergent beam transmitted to a detector which is implanted on a second card.

Abstract: An optical device for storing a coherent image in a multimode cavity makes use of two interaction media in which photoinduced phase gratings are recorded. By way of example, these media are photorefractive media. A first wave designated as an object wave travels through the cavity and interferes in each of these two media with a pumping wave in order to permit energy transfer from the pumping wave to the first wave.