| 摘要 |
PROBLEM TO BE SOLVED: To provide a new beat signal generating device which can stabilize the frequency of the beat signal which is generated from the device with respect to the fluctuations of the ambient temperature and the injection current of a laser diode, and in addition, can change the frequency of the beat signal. SOLUTION: A beat signal generating device is composed of a waveguide type optically coupling element 1 having at least two or more input ports for inputting light, at least one or more output port for outputting light, and an optical waveguide 11 provided with an optically coupling section 12, which connects the input ports with the output port and optically couples inputted light on a substrate 10 and a semiconductor laser oscillator 2 which is a light source for inputting light to each input port and provided with laser diodes by the number of the input ports. In the generating device, a grating is formed as an external resonator between the input ports and optically coupling section 12, and the oscillator 12 is oscillated at the reflection frequency of the grating.
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