| 摘要 |
PURPOSE:To provide the light frequency shifter of a thin-film waveguide type which is high in conversion efficiency and can take a wider range of frequency shift quantity. CONSTITUTION:The input light of the waveform cos(wt) from a light input part 10 is divided to four guided light rays of an equal light power by branching parts 12, 14, 24. The waveforms of the guided light rays propagating in a waveguide 15A are modulated by optical phase modulators 6A, 6B to cos[omegat+phi(t)], the waveform in a waveguide 15B to cos[omegat-phi(t)] and the waveguide in a waveguide 17 to waveform=2cos(omegat)cos[phi(t)]=2cos(omegat)co[(2pi/T)t]. The guided light in the waveguide 25A is modulated by an optical phase shifter 4 and optical phase modulators 8A, 8B to sin[omegat+phi(t-T/4)], the guided light in the waveguide 25B to sin[omegat-phi(t-T/4)], the guided light in the waveguide 27 =2sin(omegat)cos[2pi/T)(tT/4)]=2sin(omegat)sin[(2pi/T)t]. Then, the output light from an output light part 20 is made into total of both=2cos[omegat-(2pi/T)t]=2cos{[omega-(2pi/ T)]t} and only the (2pi/T) is shifted in light frequency. |
