Ultrafast air-optical switch using complex refractive index changes of thin films containing photochromic dye

An all-optical switch has been proposed based on photoinduced changes of an imaginary part of complex refractive index in a composite thin film made by silver and polymer thin films containing photochromic dye. Very fast switching on and switching off of a reading beam was demonstrated at the incident angle of guided wave mode using a photochromic spiropyran-doped polystyrene thin film and a ns pulsed laser as a writing beam. These responses were caused by the changes of an extinction coefficient due to photochromism. No applied power was required to hold the switched state. (C) 1997 American Institute of Physics.