PURPOSE: To obtain the device formed by using an optical refractive index crystal having a photorefractive effect is high by utilizing fibrous crystal body of an iron-doped LiNbO3 or LiTaO3 mounted with a visible light absorptive filter.
CONSTITUTION: The single crystal optical fiber of the crystal base material grown by the pulling up method of providing a bottomless circular conical vessel which melts the crystal base material essentially consists of the iron-doped LiNbO3 or LiTaO3 in a heating furnace, heating the crystal base material therein, drawing the melt of the crystal base material in the form of the fiber out of the lower part of the vessel and crystallizing the drawn out single crystal fiber while pulling down the fiber without using a nozzle or the reduced-diameter fiber single crystal cut out of the single crystal bulk of the base material grown by a pulling up method is used for a photorefractive hologram crystal member. This single crystal fiber is formed by mounting the reduced diameter fiber by using a visible absorption filter.
KITAYAMA KENICHI
YOSHINAGA HISAO
NIPPON TELEGRAPH & TELEPHONE