Beam intensity control for semiconductor laser - has photodiode whose current leads are galvanically separated from those of semiconductor laser

摘要

The semiconductor laser has two light emitting surfaces, one being optically coupled to a glass fibre, while the other one being optically coupled to a photodiode (4) for detection of the laser radiation intensity. The current leads (32,33) of the laser (33) and the current leads (42,43) of the photodiode are galvanically separated. Further glass fibre is preferably arranged between the second light emitting surface inthe form of a window (37) and the photodiode. Alternately, an optical component may be inserted between thin second light emitting window and the photodiode. This arrangement prevents the photodiode current to be affected by the laser current which is of much greater strength. Such an effect would limit the laser modulation to a few Mbit. The laser assembly is mounted in an electrically conductive housing (1).