JPH05249506

PURPOSE:To provide the optical switch of an optical path switching type formed by using a liquid crystal to be used for light signals, light signal processing, etc. CONSTITUTION:This optical switch is constituted by having a liquid crystal cell 15 which is formed by crimping a chiral nematic liquid crystal 14 between two sheets of glass substrates 12 and 12 having transparent electrodes 11 on the surfaces facing each other, an optical fiber 17 for input as a first waveguide for making signal light 16 incident on the liquid crystal cell 15 and optical fibers 18, 19 for emission as a second waveguide and third waveguide disposed in the positions where the reflected light and transmitted light from the liquid crystal 15 are taken out. Cholesteric-nematic phase transition is controlled by changing the electric field or magnetic field between the transparent electrodes, by which the signal light 16 entering from the first waveguide 17 is switched between the second waveguide 18 and the third waveguide 19.