PURPOSE: To easily perform an optical ON/OFF operation by an optical input itself by separating the gain peak of a medium in an active region from Bragg's wavelength of a diffraction grating, and forming a semiconductor layer for transmitting irradiated light at the top of the region.
CONSTITUTION: A laser is oscillated by a frequency different from Bragg's wavelength of a diffraction grating. Thus, the gain peak of the active medium is separated from Bragg's wavelength, and a laser end face 20 is coated on both sides with high reflection films. Accordingly, oscillated light is diffracted by the diffraction grating, irradiated toward the top of the laser, but directed obliquely upward, and shielded by a slit 19. Thus, it becomes apparently OFF as the laser. This laser is oscillated in the same frequency as that of signal light 22 by its injection synchronization, diffracted light is perpendicularly irradiated toward the top of the laser, and the slit 19 formed at the top can be transmitted perpendicularly. Thus, the optical ON/OFF operation can be performed by the light input itself of the light 22.
KOJIMA KEISUKE
HISAMA KAZUO
HAMANAKA KOICHI
