OPTICAL TRANSMITTER AND OPTICAL COMMUNICATION SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide an optical transmitter which gives the satisfactory transmission characteristic of a main signal and which can suppress stimulated Brillouin scattering (SBB) with simple constitution by overlapping a signal for suppressing the intensity modulation of a light carrier beam owing to frequency or phase modulation with the main signal. SOLUTION: The carrier beam CB is modulated in an optical converter 4 based on the main signal MS and a light signal OS is transmitted to an optical fiber transmission line 6 from the optical modulator 4. An SBS suppression circuit 10 frequency-modulates or phase-modulates the carrier beam CB based on a low frequency signal LS so that a threshold by which the light signal OS causes SBS in the optical fiber transmission line 6 becomes large. A phase inverter circuit 12 receives the low frequency signal LS and generates an opposite phase signal IS having the opposite phase. The opposite phase signal IS is overlapped with the main signal MS in an overlap circuit 14. The overlap signal SS which is thus obtained as a resultis supplied to the optical modulator 4. Thus, the satisfactory transmission characteristic of the main signal MS is given and the SBS can be suppressed.