Metal-free electric-field probe based on photonics and its EMC applications

To sustain electromagnetic compatibility (EMC), a metal-free electric-field probe is important because of its less invasiveness in electromagnetic field. This article describes a candidate of the metal-free electric-field probe based on photonics, its frequency response, and EMC applications The probe consist s of a 1 mm × 1 mm × 1 mm CdTe crystal mounted on the tip of an optical fiber, which theoretically possesses the potential to cover the frequency band from below megahertz to terahertz. We utilize a capacitor, GTEM-Cell, and standard gain horn antennas for applying a free-space electric field to the optical probe at frequencies from 20 kHz to 1 GHz, from 1 GHz to 18 GHz, and from 10 to 180 GHz, respectively. An electric-field measurement demonstrates its flat frequency response within a 6-dB range from 20 kHz to 50 GHz except for the resonance due to the piezo-electric effect at a frequency around 1 MHz. The sensitivity increases due to the resonance of the radio frequency wave propagating in the crystal at the frequencies higher than 50 GHz. These experimental results demonstrate that the optical electric-field probe is a superior tool for the wideband measurement which is impossible with conventional probes such as a dipole, a loop, and a horn antenna In transient electrostatic discharge measurements, electric-field mapping, and near-field antenna measurements, the optical electric-field probe provide the useful information for the deterioration diagnosis and the lifetime prognosis of electric circuits and devices These applications of the optical electric-field probe are regarded as promising ways for sowing the seeds of evolution in electric-field measurements for antenna measurement, EMC, and EMI.