In a signal regeneration device in which recovery of a signal quality which has been degraded during transmission in optical communication and extension of a transmission distance are achieved, the most representative method of quantizing an optical phase is a phase sensitive amplifier (PSA) and a technique that utilizes an optical parametric process through use of a highly nonlinear optical medium, but there is a demand for a technique of quantizing an optical phase which is not accompanied with an optical parametric gain, has small-sized elements, is easily integrated, and does not require high power pump light. By a technique of a hybrid optical phase squeezer (HOPS), when a phase of input light is quantized to M levels (M>2), phase conjugate light of the input light and (M−1)th phase harmonic light of the input light are subjected to power modulation to be coherently added, so that quantization of the optical phase is performed through use of a simple four-wave mixing (FWM) that is not accompanied with the optical parametric gain and a general optical amplifier by using a general nonlinear optical medium such as silicon, and accordingly, a GER of equal to or higher than 30 dB can be obtained, even if a nonlinear optical element having a low nonlinearity is used.