| 摘要 |
PROBLEM TO BE SOLVED: To easily improve wavelength stability by adjusting the temperature of a laser diode, controlling the transmission wavelength and bringing the laser diode and an optical wavelength filter into thermal contact so as to keep both at an almost equal temperature. SOLUTION: A laser diode 1 inside a module package outputs the laser beam of a prescribed transmission wavelength and an optical fiber 9 is optically coupled to the laser diode 1 and leads out the laser beam outputted from the laser diode 1 to the outside. An optical wavelength filter 3 is provided with a cut-off wavelength almost same as the transmission wavelength of the laser diode 1. One or more photodiodes for wavelength control transmits or reflects a part of the light output of the laser diode 1 to the optical wavelength filter, then, receives it and outputs the received light level. Then, a Peltier element 6 controls the transmission wavelength of the laser diode 1. Further, a thermal contact means brings the laser diode 1 and the optical wavelength filter 3 into thermal contact so as to keep both at the almost same temperature.
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