Sensitivity Enhancements to Photonic Electric Field Sensor

This paper describes an electrode-less, all-optical, wideband electric field sensor fabricated in an electro-optic lithium niobate substrate. The sensor component is an integrated optic Mach-Zehnder interferometer. The electric field sensor uses the electro-optic properties of lithium niobate to modulate the phase of the light propagating in each arm of the Mach-Zehnder interferometer. The phase modulated light is then converted to intensity modulation at the output of the interferometer. The unique feature of the sensor device is that the orientation of the crystal in one arm of the MachZehnder interferometer is inverted to provide push-pull optical modulation for an applied electric field. Optical fibers are connected to the input and output of the sensor device. The basic device is an all-dielectric intensity modulator. The ability to operate the sensor without the use of any metal antenna permits its use in extremely high field conditions without any danger of damaging the sensor. The optical fiber connections provide optical isolation to the instrumentation to protect the instrumentation from possible overload conditions. The electrode-less sensor is designed specially for measuring high field strengths similar to the conditions in electromagnetic pulse, high power microwave and high voltage power lines. Sensitivity improvements are possible by using carrier suppression techniques.