METHOD FOR DRIVING OPTICAL SUB-CARRIER MODULATOR AND DRIVING CIRCUIT

摘要

PROBLEM TO BE SOLVED: To suppress an unnecessary side robe superposed on an output light sub-carrier and to suppress a noise owing to the interference of a light area by compressing the pulse time width with an input data signal and driving a light sub-carrier modulator through the use of a driving signal where a higher harmonic component is suppressed. SOLUTION: The pulse time widths of input data and inverted input data are compressed by pulse compressors 5a and 5b. The higher harmonic component of a pulse is suppressed in LPE 6a and 6b and a prescribed bias voltage (V1+V2)/2 is superposed. The driving voltage of an MZ modulator 13a and the driving voltage of an MZ modulator 13b are obtained. In light sub-carries outputted form the MZ modulators 13a and 13c, overlap does not occur in a complementary switch operation by the compression of the pulse time widths of respective driving voltages. Intensity strength by interference in a light area is suppressed. Also, an unnecessary side robe which is superposed on the output light sub-carrier is suppressed by the suppression of the higher harmonic component of the pulse.