By arranging mirrors on both sides of the electro-optic crystal to form a Fabry-Perot cavity, the laser can travel back and forth multiple times inside the crystal, increasing the modulation depth of the laser phase in the crystal by the externally applied electric field, thus achieving high-sensitivity electric field measurement. A mathematical model of the transfer function for the Fabry-Perot type electro-optic crystal electric field sensor is established, and the response characteristics and their influencing factors of the sensor are calculated. The results show that the higher the reflectivity of the Fabry-Perot cavity is, the greater the improvement in measurement sensitivity will be, when the reflectivity is 0.99, the sensitivity can be increased by nearly a hundred times compared with the conventional interferometric sensing structure. The light absorption coefficient of the electro-optic crystal and the laser incident offset angle will affect the measurement sensitivity. The smaller the light absorption coefficient and the laser incident angle, the higher the measurement sensitivity.
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