Patent ID: 7372881

Claim:
A control device, comprising: an object to be controlled, the object to be controlled having a cut-off frequency and comprising: a semiconductor laser, and an optical filter which receives light from the semiconductor laser and whose transmissivity varies with the wavelength of the light; and a first control component controlling the optical wavelength of the semiconductor laser to a prescribed wavelength by driving a temperature control unit to control the temperature of the semiconductor laser, the first control component having a transfer function and comprising: a first input receiving a first photoelectric conversion signal representing the intensity of light transmitted by the optical filter; a second input receiving a target signal corresponding to the prescribed wavelength; and an output providing a control signal for driving the temperature control unit; wherein: the transfer function has a low pass characteristic, a plurality of poles, and a zero; the frequency of the pole having the highest frequency is higher than the cut-off frequency; and the frequency of the zero is lower than the cut-off frequency; wherein the semiconductor laser, the optical filter, and the first control component are configured to form a feedback loop.