To provide a device for shaping a waveform with the wide range of wavelength transformation.

The device is provided with a first and second non-linear loop mirrors. Each first and second mirror is provided with the following. A first coupler: It includes a first and second optical path conjugated directionally. A second optical coupler: It includes a loop optical path consisting of non-linear optical medium connected with the first and second optical paths and a third optical path conjugated directionally toward the loop optical path. A first power monitor: It detects the power of intermediate optical signal optically connected with the second optical path of the first non-linear loop mirror. A first power controller: It controls at least one power of either input optical signal or first probe light so as to increase the power detected by the first power monitor. A second power monitor: It detects the power of output optical light optically connected with the second optical path of the second non-linear loop mirror. A second power controller: It controls one power of either the intermediate optical signal or the second probe light so as to increase the power detected by the second power monitor.