Having a function of automatically adjusting the resonance frequency of the electro-optic phase modulator

The invention discloses an electro-optical phase modulator, which comprises an electro-optical phase modulating crystal, a power extraction unit, a modulating power detection unit, a coherent power detection unit, a feedback signal generating unit, an electro-optical phase modulating crystal parallel resonant circuit, a main controller unit and an electro-optical phase modulator shielding shell, wherein the power extraction unit is used for extracting the power and a driving signal of an input modulating signal and the power of a coherent signal of a phase modulator reflected signal; the modulating power detection unit is used for converting the power of the extracted modulating signal into a voltage value; the coherent power detection unit is used for converting the extracted power of the coherent signal into a voltage value; the feedback signal generating unit is used of providing a feedback signal according to signals output by the modulating power detection unit and the coherent power detection unit; the main controller unit is used for acquiring and judging the feedback signal provided by the feedback signal generating unit, controlling the inductance value of the parallel resonant circuit according to a judgment result and automatically changing the resonant frequency point of the phase modulator till the resonant frequency point is matched with a modulating signal frequency; the resonant frequency of the phase modulator is always matched with a modulating signal frequency value output by a modulating power supply; and the electro-optical phase modulator shielding shell is used for protecting each component inside the electro-optical phase modulator and isolating external electromagnetic interference signals.