| 摘要 |
<p>The present inventions aims at providing a gain control unit which has a temperature compensating function capable of flexibly coping even with a gain wavelength characteristic which fluctuates depending on ambient temperature, to thereby provide an optical amplifier, of small size and simple constitution, capable of realizing a gain wavelength characteristic which is stable over a wide temperature range. To this end, the gain control unit according to the present invention comprises an optical transmission line formed with a plurality of long period fiber gratings (LPG) having such constitutions that loss wavelength characteristics thereof are mutually different and the respective loss wavelength characteristics have mutually different temperature dependencies, and the characteristics of the LPG's are set corresponding to the gain wavelength characteristic of the optical amplifier and a temperature dependency of the gain wavelength characteristic of the optical amplifier, respectively. In this way, there can be automatically performed a gain compensation corresponding to a temperature characteristic. <IMAGE> <IMAGE></p> |
