OPTICAL LIMITER CIRCUIT

摘要

PROBLEM TO BE SOLVED: To suppress the waveform distortion and noise of very high rate signal light with a simple configuration that does not include a retiming means and to expand transmission distance and transmission capacity by inputting input signal light and auxiliary light to an optical fiber whose zero-dispersion wavelength is equal to input signal light wavelength or has value that is slightly shifted to a short wavelength side and inducing a four wave mixing process. SOLUTION: Input signal light and auxiliary light which are multiplexed by an optical multiplexer 13 are inputted to an optical fiber 16 through a polarizer 15. Output light of the fiber 16 is inputted to an optical filter 17 and only an input signal light component is outputted. An optical amplifier 11 amplifies input signal light power up to the extent where four wave mixing sufficiently takes place in the fiber 16. When the zero-dispersion wavelength of the fiber 16 is set to a short wavelength side from input signal light wavelength, the influence of an optical Kerr effect corresponding to the input signal light power appears on a large degree and output signal light power to the input signal light power shows a saturation characteristic with certain input signal light power as threshold and operates as an optical limiter circuit.