Abstract: The disclosure is directed to an improved semiconductor laser device which includes a first light deriving optical waveguide connected approximately perpendicularly to a light exit face at one side, a second light deriving optical waveguide connected approximately perpendicularly to another light exit face at the other side and having an optical axis different from that of the first light deriving optical waveguide, and a light emitting optical waveguide subjected to optical coupling with a periodical diffraction grating for optical resonance, and connected to end portions of the first and second light deriving optical waveguides within the semiconductor laser device.

Abstract: A micro-displacement measuring apparatus using a semiconductor laser, comprises a compound resonator system containing the semiconductor laser, and a light detector receiving the light from the semiconductor laser, and with the compound resonator system being constructed such that light from said laser irradiates an object to be measured and the reflected light therefrom returns to the semiconductor laser. The light detector detects and measures the number of fluctuations and the level of the optical output of the laser to determine the displacement of the object and of the direction of the displacement of the object, respectively.