Patent ID: 7848659
Filing Date: 2010-12-07
Classification: G02F,H04B

Abstract:
1. An optical transmitting apparatus for transmitting a modulated optical signal corresponding to a data signal, comprising: a phase shift unit to control a phase of at least one of a first optical signal and a second optical signal, obtained by splitting an optical input, so that the first and the second optical signals have a phase difference on an optical waveguide; a data modulator unit to modulate the first and second optical signals using the data signal on the optical waveguide; an extraction unit to extract at least a part of continuous frequency components except for a given frequency from a modulated optical signal in order to detect a change of spectrum of the modulated optical signal, the modulated optical signal being obtained by coupling the first and the second optical signals modulated by said data modulator unit, and the given frequency being an integral multiple of a symbol frequency; and a phase difference control unit to control said phase shift unit using the continuous frequency components extracted by said extraction unit, wherein said extraction unit comprises: a photodetector to detect the modulated optical signal; and a filter to pass the at least a part of the continuous frequency components except for the given frequency, which is an integral multiple of the symbol frequency, from an output signal of said photodetector, and wherein said filter is a band-pass filter with a cut-off frequency lower than the symbol frequency.