An all-dielectric, 3-axis electric field sensor using quasi-longitudinally configured electro-optic crystals

We describe a stabilized, all-dielectric, 3-axis electric field sensor using electro-optic (EO) crystals. By directing the laser probe quasi-longitudinally with respect to the optic axis of the crystal, we have improved stability by three orders of magnitude and substantially reduced phase noise. While the modulation depth of the output signal is slightly reduced, overall sensitivity is greatly improved due to the larger signal to noise ratio. Unlike conventional EO sensors, measurements can be made with 50 meters of optical fibers without excessive noise. Additionally, the sensor and fibers can be moved during measurements without the need for compensation optics or recalibration. This makes the sensor very practical for actual field test applications and attractive for potential commercial use.