| 摘要 |
PURPOSE:To obtain the optical waveguide which has small return light to a semiconductor laser. CONSTITUTION:When the wavelength of incident light on the optical waveguide as to incident light on the light incidence end surface 2a of the clad layer 2 of the optical waveguide and the light incidence end surface 3a of the optical waveguide layer 3 is denoted as lambda and the refractive index of the medium of the optical path for the incident light up to the optical waveguide is denoted as (n), the optical path difference DELTAL between the incident light on the incidence end surface 2a of the clad layer 2 and the incident light on the incidence end surface 3a of the optical waveguide 3 is made to be an odd multiple of quater wave length of incident light i.e., (2i+1) lambda/4n (i: 0, 1, 2, 3<). Consequently, the phase of reflected light from the incidence end surface 2a of the clad 2 becomes reverse to the phase of reflected light from the incidence end surface 3a of the optical waveguide 3, so the laser light which is reflected by the end surface of the optical waveguide is not supplied as return light to the semiconductor laser 4 to eliminate the unstableness of the operation of the semiconductor laser 4 such as variation in the oscillation output of the semiconductor laser 4 and a mode hop phenomenon due to the return light. |
