| 摘要 |
PROBLEM TO BE SOLVED: To reduce the cost of an input filter device of an optical frequency converting circuit device by forming a switchable input filter device with plural wavelength channel filters of a wavelength multiplexer/demultiplexer. SOLUTION: An input optical signal of a required frequency that goes through an input fiber device EFA which consists of 1:n filter switch Sn and a wavelength multiplexer/demultiplexer DM together with an optical signal of a prescribed frequency of a pump laser PL which inputs in the opposite direction are inputted to a frequency converter U to be a pump laser signal that is modulated with an input optical signal. The signal is outputted to output side optical fiber A through a fixed filter FA which eliminates noise through a coupler and the converter U. With this structure, a signal is conducted from an input fiber which should not convert an optical frequency to an output fiber. |
