OPTICAL SUBCARRIER FREQUENCY MODULATOR

摘要

PROBLEM TO BE SOLVED: To deal with a high carrier frequency at a low cost and to widen the modulation band by multiplexing an optical carrier demultiplexed with a wavelength filter with a frequency modulated optical sub-carrier outputted from an optical frequency shifter. SOLUTION: Two waves adjacent at a 60 GHz interval of a laser beam from a mode lock laser diode(MLLD) 1 are cut out by an array waveguide diffraction grating(AWG) 2. An emission beam from a fiber collimator 3a is made incident on an acoustooptical modulator(AOM) 4 as a parallel beam. A modulator 13 applies an output of an oscillator 11 to the AOM 4 when a digital signal is '1', and doesn't output when '0'. The optical sub-carriers transmitted or diffracted by the AOM 4 to be frequency modulated are made incident on a 3 to 1 coupler 6 respectively through the fiber collimators 3b, 3c. The 3 to 1 coupler 6 multiplexes the optical carrier of an optical frequency f0 demultiplexed by the AWG 2 with the optical sub-carrier of the optical frequencies f1 (f2) frequency modulated by the AOM 4 to output it.