| 摘要 |
PROBLEM TO BE SOLVED: To detect abnormality of an optical signal surely, even if noise is mixed with the input to an optical receiver or generated therein. SOLUTION: The system for detecting abnormality of an input signal to an optical receiver comprises a first optical band-pass filter means 103 which causes only the wavelength component of an input optical signal to pass through, a second optical band-pass filter means 202 which causes the wavelength component other than that of the optical signal to pass through, and means 105, 109, 201, 203, 204, 205, 206 for deciding abnormality of an input optical signal, based on the level difference between an optical signal passing through the first optical band-pass filter means and an optical signal passing through the second optical band-pass filter means. |
