| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical frequency modulator which performs only optical frequency modulation without performing light intensity modulation. SOLUTION: A vertical resonator type surface light emitting diode (VCSEL) 4 is used as a laser diode. The value of a bias current supplied from a constant-current source 3 to the VCSEL 4 is brought under the feedback control of a bias control circuit 6 to maximize the output of laser light L output from the VCSEL 4. At the same time, the gain of a variable gain amplifier 1 supplying a signal current id obtained by amplifying a data signal (d) to the VCSEL 4 is brought under the feedback control of a frequency shift control circuit 10, so that the frequency shift of the laser light L output from the VCSEL 4 matches a predetermined specified frequency shift. Consequently, the optical frequency modulator operates as a pure frequency modulator which performs only optical frequency modulation, and does not perform light intensity modulation. COPYRIGHT: (C)2007,JPO&INPIT
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