JPS5794715A - Optical switch - Google Patents

Abstract

PURPOSE:To reduce a crosstalk, by installing a polarization surface separating element and a wedge-shaped polarizing and separating element whose refractive direction is different by polarization, before and behind a polarization surface converting element. CONSTITUTION:An incident light beam is divided by a polarization separating element 21, a transmission light beam and a reflected light beam are made to pass through Faraday rotors 22, 22', respectively, rotate the polarization surface by +45 deg. or -45 deg., and after that, are made incident to wedgelike polarizing and separating elements 23, 23' for reflecting the light beams in the direction being a little different from the 2 polarization surfaces meeting at right angles. The reflected rays from the polarizing and separating elements 23, 23' are made to pass through the Faraday rotors 22, 22' once again, are rotated by +45 deg. or -45 deg. in the same direction, and projected light beams of the rotors 22, 22' become polarized beams meeting at right angles to original beams, therefore, in the inside of the separating element 21, light beams from the rotor 22 transmits and loght beams from the rotor 22' are reflected, and they advance to 24 or 24'. Whether the light beams pass through the optical path 24 or 24' depends on the direction of a magnetic field applied to the Faraday rotor, therefore, it is switched by the direction control of a magnetic field.