Recent Advances in the Design of Electro-Optic Sensors for Minimally Destructive Microwave Field Probing

Abstract

In this paper we review recent design methodologies for fully dielectric electro-optic sensors that have applications in non-destructive evaluation (NDE) of devices and materials that radiate, guide, or otherwise may be impacted by microwave fields. In many practical NDE situations, fiber-coupled-sensor configurations are preferred due to their advantages over free-space bulk sensors in terms of optical alignment, spatial resolution, and especially, a low degree of field invasiveness. We propose and review five distinct types of fiber-coupled electro-optic sensor probes. The design guidelines for each probe type and their performances in absolute electric-field measurements are compared and summarized.

Simple optical transformer system for intense electric field and voltage sensing

“…The EO sensors are mated to a few meters (or longer if necessary) of totally enclosed 1550 nm fiber-optic link. Details of the optical parts -from the polarization-controlled laser, the optical link which circulates from the EO sensor, to the photo detector -are discussed in our previous work [6]. The electric fields are demodulated in electrical signals at the detector and read through a lock-amplifier in the voltage unit.…”

“…3(c) is set along the E z direction, if the laser polarization is linear and also set along to the z-(or x-) direction, the laser beam undergoes only n e (or n o ) throughout the wafer. We utilized this 'birefringence-free' condition to implement a 'thick-interferometric' type of EO sensor [6].…”

Full vectorial mapping of the complex electric near-fields of THz resonators

“…Another approach uses electro-optic crystals as an external near-field probe. 40 This technique is limited by low sensitivity as well as partial invasiveness to the near-fields. Out-of-plane magnetic fields have been calculated from direct measurements of in-plane electric fields using photo-conductive (PC) antennas on substrates.…”

Polymeric Integrated-Optic Bias Chip for Optical Voltage Transducers

“…OVTs measure the phase retardation caused by the electrooptic effect in nonlinear crystals such as LiTaO 3 , LiNbO 3 , and BGO subject to an electric field to be measured [6], [8], [9]. In these sensors, the operating point has to be adjusted to an initial phase difference of π/2 between the arms of the optical interferometer.…”