Optical data recording and reproducing system with control of high frequency superposed signal applied to semiconductor laser

摘要

In an optical data recording and reproducing system in which recording and reproducing data are carried out with a semiconductor laser, circuitry is provided to reduce the level of a high frequency current to be superposed on the laser during a data recording operation relative to the level during a data reproducing operation, to provide laser output only when necessary, to prolong laser life.