| 摘要 |
PROBLEM TO BE SOLVED: To improve single-wavelength oscillation by forming a light absorbing body in the waveguide on the non-exit side and forming an antireflection film (AR coat) only on one side, or forming a light absorbing structure or light absorbing film on the non-projection face and obviating the reflection prevention film. SOLUTION: An antireflection film (AR coat) 5 is formed only on the end face on one side (exit side) where laser light is taken out, and a clad layer 2 is formed on the other side (underside) by epitaxial growth. Thereafter, the portion marked with 'A' is shaven off by etching. On the upper clad layer 2a shaven by etching, a substance (e.g. niello) 7 which absorbs light with an oscillation wavelength is vapor-deposited or a compound semiconductor (e.g. InGaAs) 8 is formed by epitaxial growth. The light trapped in the waveguide 1 cannot be trapped by the thin clad layer 2a and leaks at its upper part. The light is then absorbed by the light absorbing body (niello 7, InGaAs 8) positioned thereon.
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