| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical signal processing circuit that adopts a multi- value differential phase modulation signal and that can easily set an optical signal modulation threshold. SOLUTION: The optical signal processing circuit comprises an optical input port 11, a photocoupler 12, an optical delay guide path pair 13 connected to the photocoupler 12 and comprising two optical guide paths whose length differs from each other, a multi-mode interference photocoupler 14 which acts like an optical hybrid element, and an optical output port 15. The photocoupler 12 divides the optical signal pulse received from the input port 11 into two which are led to the optical delay guide path pair 13 to which a delay time is set to be the same as the time of a time slot τ of the input signal, thereby a threshold is easily set for receiving the optical signal subjected to multi-value differential phase modulation. |
