| 摘要 |
PURPOSE: To efficiently and exactly control the emitted light wavelength of a light emitting element by outputting a different prescribed detect signal corresponding to whether the emitted light wavelength is longer or shorter than a prescribed wavelength and controlling a temperature control means. CONSTITUTION: When light outputted from a light emitting element LD 32 is longer than a desired wavelength, the output light is guided to a light receiving element 44 based on the detect signal outputted from a branching filter 40, and converted to an electric signal. Afterwards, it is amplified by a preamplifier 48 and supplied to the plus side of an error amplifier 52 and no output light is made incident to a light receiving element 46. Then, the amplifier 52 amplifies the inputted signal, a current corresponding to this signal is inputted to a Peltier element 36, the temperature of the LD 32 is decreased, and the transmitted wavelength is shifted to the short wavelength side. Besides, when the light outputted from the LD 32 is the light of a wavelength shorter than the desired light, it is guided to the light receiving element 46 by a branching filter 42 and guided through a preamplifier 50 to the minus side of the amplifier 52. Then, the current inputted to the element increases the temperature of the LD 32 and the oscillated wavelength is shifted to the long wavelength side. |
