Photodetector built-in type semiconductor laser

Abstract

Abstract PURPOSE:To increase photocurrents from a photo-diode, and to stabilize an optical output by forming a reflecting film with the exception of a beam extracting section at a central section in window glass and introducing reflected beams by the reflecting film to a photodetector. CONSTITUTION:A reflecting film 26 is formed to a window glass section except a beam extracting section at the center in window glass 25. Beams within approximately + or -30 deg. in beams 27 projected from the front of a semiconductor laser- chip 21 are projected through window glass 25, but residual beams are reflected to the inside by the reflecting film 26. Driving currents for the laser-chip 21 are fed back by an APC circuit by receiving the reflected beams 28 by a photodetector 22 (a PIN photo-diode), and an optical output from the front is stabilized. Accordingly, the photocurrents of the PIN photo-diode increase, and the instability of the optical output resulting from the unbalance of front beams and back beams when there are returned beams is also removed.

Inventors

• 👤 Yorifumi Inada
• 👤 順史 稲田
• 👤 Kazuhisa Murata
• 👤 和久 村田

Bibliographic Details