Light output monitor from semiconductor laser

摘要

Light or emission output control is from a semiconductor laser of the type used for telecommunications or similar equipment where a stable median value output is required. The semiconductor laser (1) may emit a forward (L) light beam for operational applications and a reverse beam (BB) which is used for control purposes. A photodetector (11) measures the output and feeds a signal into a comparator (14), a second input is fed from a reference source (13).The comparator output is fed to a timing circuit (16) which responds to start commands (T1) so that the control signal is fed through to the output device control (19) in the correct time slot. The time slot is one in which no transmission signal is passing through the system and control for it is generated by the oscillator (15), counter (16), D/A converter (17) and current amplifier (18) stages