Patent ID: 8260149

Claim:
A carrier-suppressed optical pulse train generating device comprising: a first electric modulation signal generator generating and outputting a first electric modulation signal that is synchronous with a clock signal; a second electric modulation signal generator generating and outputting a second electric modulation signal of a same frequency as the first electric modulation signal and to which a phase difference of δ radians is provided, where δ is a real number satisfying 0≦δ ≦π; and a Bragg reflection semiconductor laser, wherein the Bragg reflection semiconductor laser comprises: first and second sampled grating regions at which are formed sampled gratings that are structured such that a short-period grating is incorporated-in within one period of a long-period grating, and that have a double period structure of a long period and a short period; first and second optical intensity modulating regions having a function of modulating optical intensity; a gain region at which an inverted distribution is formed; and first and second phase adjusting regions at which an equivalent refractive index is variable, wherein a Bragg reflection semiconductor laser structure is formed by disposing, in series, the first optical intensity modulating region, the gain region and the first and second phase adjusting regions, between the first sampled grating region and the second sampled grating region, the second optical intensity modulating region is outside of a region sandwiched by the first sampled grating region and the second sampled grating region, and is structured by being disposed in series and adjacent to either one of the first sampled grating region and the second sampled grating region, a wavelength of oscillation light of a Bragg reflection semiconductor laser structural portion can be varied by changing equivalent refractive indices of the first and second sampled grating regions and the first and second phase adjusting regions, the laser is mode-lock-operated by modulating light transmittance of the first optical intensity modulating region by the first electric modulation signal, and can be made to output a carrier-suppressed optical pulse train, and a duty ratio of an optical pulse structuring the carrier-suppressed optical pulse train can be controlled by modulating light transmittance of the second optical intensity modulating region by the second electric modulation signal.