Semiconductor optical signal amplifier

A semiconductor optical signal amplifier, comprising:

• an active layer, made of an amorphous semiconductor that amplifies a signal intensity of an input light by stimulated emission;
• and
• a detection electrode, detecting a change in carrier density in the active layer, wherein
• the active layer has a point defect that serves as a recombination center forming an energy level in a band gap of the amorphous semiconductor, and
• a light with an energy smaller than a band gap energy of the amorphous semiconductor is amplified by transition via the energy level.

A semiconductor optical signal amplifier, comprising:

• a first end face;
• a second end face, arranged apart from the first end face;
• a first semiconductor region of a first conductive type, arranged between the first end surface and the second end surface;
• a second semiconductor region of a second conductive type opposite to the first conductive type, arranged between the first end face and the second end face;
• an active layer, arranged between the first end surface and the second end surface, and sandwiched between the first semiconductor region and the second semiconductor region, wherein the active layer is made of an indirect transition type semiconductor that amplifies a signal intensity of an input light by stimulated emission;
• and
• a first electrode, connected to the first semiconductor region;
• a second electrode, connected to the second semiconductor region and detecting a change in carrier density in the active layer by a potential difference from the first electrode, wherein
• the active layer has a point defect that serves as a recombination center forming an energy level in a band gap of the indirect transition type semiconductor, and
• a light with an energy smaller than a band gap energy of the indirect transition type semiconductor is amplified by transition via the energy level.