| 摘要 |
PROBLEM TO BE SOLVED: To obtain a semiconductor laser with a modulator having an optical monitor used as a source of a light communication system, by providing an optical monitor on a part of light wave guide. SOLUTION: A semiconductor laser 20 with a modulator comprises a modulator 21, an optical monitor 22 and a semiconductor laser 23 along a light wave guide 5. Thickness of a multiple quantum well is set to be MQW film thickness (modulator 21)<MQW film thickness (optical monitor 22)=MQW film thickness (semiconductor laser 23), so thatλPL (modulator 21)<ΛPL (optical monitor 22)=λPL (semiconductor laser 23). A low-reflection film is provided on the end face of the modulator 21 side, that is an emitting surface of an emitted light (the front emitting surface 2), and a high-reflection film is formed on the end face of the semiconductor laser 23 side (the back emitting surface). For example, the low-reflection film is 1% or less, and the high-reflection film is 90% or more in reflectance.
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