Patent ID: 7631378
Filing Date: 2009-12-15
Classification: G02F,H04B

Abstract:
1. An optical waveform shaper, comprising: a polarization device which splits an optical signal into first and second polarization element being perpendicular to one another; first and second optical waveform shaping units which carry out waveform shaping for the first and second polarization elements, respectively; and a polarization device which carries out the polarization-coupling of the outputs from said first and second optical waveform-shaper units, wherein each of said first and second optical waveform shaping units is an optical waveform shaper including a first interferometer and a second interferometer, wherein one of the first and second interferometers has a first transfer function, where the second order derivative of output optical power in respect to the input optical power is positive when the input optical power is zero or substantially zero, and the output optical power shows substantially periodic changes with respect to the input optical power, the other of the first and second interferometers has a second transfer function, where the second order derivative of output optical power in respect to the input optical power is negative when the input optical power is zero or substantially zero, and the output optical power shows substantially periodic changes with respect to the input optical power, each of the first and second interferometers has first and second input ports and first and second output ports, an optical path from the first input port to the first output port in each of the first and second interferometers provides the first transfer function, and an optical path from the first input port to the second output port in each of the first and second interferometers provides the second transfer function, an input optical signal is provided to the first input port of the first interferometer, the output optical signal from the first output port of the first interferometer is guided to the first input port of the second interferometer, and the second output port of the second interferometer is coupled to an output port of the optical waveform shaper, and wherein the first and second transfer functions are determined in such a way that a total transfer function of the first and second transfer functions satisfies the conditions of FWm/FWs>1, and Wtr<FWm, and wherein FWm is a width of a region where output power of the optical waveform shaper is substantially flat at a high-emission level with respect to input power of the optical waveform shaper, FWs is a width of a region where output power of the optical waveform shaper is substantially flat at a low-emission level with respect to input power of the optical waveform shaper, and Wtr is a width of a region where output power of the optical waveform shaper rises from the low-emission level to the high-emission level with respect to input power of the optical waveform shaper.