Organometallic thin films for erasable photochromatic laser discs

Abstract

ABSTRACTA new category of erasable optical storage media, M11 (TCNQ) films, is described. The photochromatic effect ofthis organometallic charge-transfer complex can give high contrast patterns directly produced on the film by pulsed photon beams generated from a He-Ne tube or a semiconductor laser. The patterns are erasable by the same light sourceunder different irradiating conditions. Typical experimental results were as follows: 1. For = 632.8 nm, write-in power = 16 mW, pulse duration = 300 ns; erasing power = 8 mW, pulse duration = 25 s; coefficient of contrast K > 50 % ; number of write-erase cycles N > 1000.2. For A. = 830.0 nm, write-in power — 12 mW, pulse duration = 650 ns; erasing power = 4 mW, pulse duration = 15 cs; K > 25%; N > 120. 1. INTRODUCTIONThe interaction of a laser radiation with matter in optical storage systems, known as laser discs, has receivedconsiderable attention because its storage density can be 10 - 10 bit/cm2, i.e. 10 - 100 times greater than that of any