| 摘要 |
PURPOSE:To radiate a specific laser beam to the outside at a low output and to reduce a noise by a method wherein a transparent plate having the following is installed in a radiation direction of the laser beam: a waveguide; a grating coupler designed so as to couple the specific laser beam out of a plurality of laser beams to the waveguide. CONSTITUTION:In a radiating direction of a semiconductor layer chip 1, a transparent plate 2 where a waveguide 3 and a grating coupler 4 have been manufactured on its surface is installed perpendicularly to an optical axis of a laser beam. The semiconductor laser chip 1 is driven; one part of a beam 9a on the left side is coupled to the waveguide 3 by using the grating coupler 4; it is transformed into a waveguide beam 9b; the remaining part is transmitted through the transparent plate 2 and is transformed into a transmitted beam 9c. After the waveguide beam 9b has been propagated in the waveguide 3, it is absorbed by a light absorber 5. An angle of incidence of two (center and right) beams other than the left beam is different from that of the left beam; they are not coupled to the waveguide 3 and are transmitted through the transparent plate 2; an output of the beams is changed little. |
