| 摘要 |
PURPOSE:To perform high-efficiency branching and coupling operation with small-sized constitution by arranging a coupling waveguide part made of a semiconductor material with P-N junction between an input and an output waveguide and implanting a forward current in the coupling waveguide part. CONSTITUTION:A waveguide layer in double heterostructure is constituted at the P-N junction part of the semiconductor coupling waveguide part 11 which has the P-N junction part and the forward implanted current is supplied. The implanted current makes medium of the coupling waveguide part 11 vary from loss to gain, so signal light is amplified when set almost to the peak of gain. When the double heterostructure of InGaAsP/InP is employed, the signal light has a 1.5mum wavelength band, and the coupling waveguide part 11 is 250mum long, >=20dB transmission gain is obtained. Therefore, even when 10 input and output waveguides each face each other, the gain can be compensated sufficiently even if the branch loss is 10dB and the coupling loss is 5dB, so that a 10-to-10 optical branching and coupling device having no loss can be constituted. Further, the light signal can be turned on and off by turning on and off the implanted current. Thus, an active optical coupling part with gain is obtained and the size is reduced while an angle of branching is large. |
