Patent ID: 6847053

Claim:
An optical transmitter comprising: a substrate having a concave groove which consists of a single material and having a V-groove fixing an optical fiber; a semiconductor laser diode for generating a transmission light beam forward and a monitor light beam backward, said laser diode being disposed on the substrate; and a monitor photodiode for sensing the monitor light beam of said laser diode, said monitor photodiode being disposed on a slanted side face of the concave groove; wherein an active area of said monitor photodiode has an antireflection coating, and is disposed slantingly so that an oblique angle of the active area thereof is 30 through 50 degrees to a plane including the optical axis of the radiation light from said laser diode, and is parallel to a surface of the substrate so that the monitor light beam from said laser diode directly enters the active area of said monitor photodiode.