| 摘要 |
PURPOSE:To obtain an optical FSK modulator which operates with a low voltage in a high speed in a wide band, by applying such voltage that the phase modulation waveform becomes a saw tooth wavelength. CONSTITUTION:Electrooptical crystal 1 such as LiNbO3, optical waveguide region 2 of a high refractive index formed by impurity diffusion, and electrodes 3 and 4 are provided. When the light is incident to optical waveguide region 2 and a saw tooth wave voltage is applied to electrodes 3 and 4, the phase of the emitted electric field is subjected to modulation proportional to the applied saw tooth wave voltage by the electrooptical effect. Thus, the optical frequency is given with the differential waveform and is given as the frequency shift keying (FSK) signal. Thus, the optical FSK signal is obtained by changing the momentary phase of the emitted light to a saw tooth waveform. |
