| 摘要 |
PROBLEM TO BE SOLVED: To provide a photo diode which can receive an optical signal where the wavelength is divided and multiplexed with a single element and is easy of manufacture, and an optical communication system capable of wavelength- divided and multiplexed optical communication by a simple optical circuit. SOLUTION: A photo diode 100 has first and second pin type of photodiodes 100-1 and 100-2 which have different band widths of light absorbing layers, in a stack which has a plurality of semiconductor layers stacked on an n-type semiconductor substrate 101, and they are stacked in order of smaller band width of light absorbing layers 102 and 104 from the side of a semiconductor substrate 101. The light receiving section 110 is made on the side of a pin type of photo diode 100-2 having a light absorbing layer larger in band width, and for the above two photodiodes, the same conductivity (p-type) type of contact layer is used in common in the single contact layer 3, and this photodiode can electrically convert two different wavelengths of lights. |
