| 摘要 |
The invention realizes an optical modulator which prevents occurrence of an edge breakdown and is improved in extinction characteristic and voltage resisting property. The optical modulator comprises an oxide film (12) formed as a growth inhibiting film on a compound semiconductor substrate (11) of a first conduction type, a double hetero structure including a clad layer (14) of the first conduction type, a light absorbing layer (15) and a clad layer (16) of a second conduction type successively formed in an opening of the oxide film (12), and an embedding structure (19,519) for covering over the entire double hetero structure. The optical modulator is characterized in that the carrier concentration of the clad layer (141,142) of the first conduction type exhibits a continuous variation from the semiconductor substrate (11) to the light absorbing layer (15) or the carrier concentration of the embedding structure portion (519) exhibits a variation from a low concentration to a high concentration. <IMAGE> |
