WAVELENGTH MONITOR AND LASER MODULE CONTAINING IT

摘要

PROBLEM TO BE SOLVED: To provide a wavelength monitor that can obtain high-quality photodetecting signals, and to provide a laser module containing the monitor. SOLUTION: An optical filter 101 is arranged with the light incidence-side surface of the filter 101 being inclined with respect to the direction of incidence. Consequently, the route of reflected light 113 from the incident surface of the filter 101 can be deviated largely from incident light 111 to the filter 101, and the reflected light 113 can be prevented from being made incident to a semiconductor laser element or photodetector.