Electromagnetic field components: their measurement using linear electrooptic and magnetooptic effects

Abstract

Vector components of alternating electric and magnetic fields can be measured with excellent sensitivity and time resolution using a laser system employing Pockels effect or Faraday effect materials as field sensors. This technique offers the advantages of being passive and remote; the sensor material requires no power source and can be interrogated by a remotely located laser transmitter and receiver with no connecting wires or electrodes. This paper analyzes the sensitivity of the electrooptic and magnetooptic methods and derives new figures of merit for materials used as sensors in these applications. Experiments evaluating the temperature coefficients of sensitivity and demonstrating that sensitivities of 0.06 V/cm and 0.5 G can be achieved easily are described.

Fast, sensitive magnetic-field sensors based on the Faraday effect in YIG

“…Massey et al [2] calculated that the noise-equivalent magnetic field for a YIG sensor 2 mm in diameter and 1 cm long with a shot-noise limited optical system should be on the order of 100 pT/dHz. Such a sensor, for which pollsat = 10 mT, would possess a dynamic range of 160 dB (for a noise bandwidth of 1 Hz).…”

“…In one of the first papers to consider the use of iron garnets as magnetic-field sensors, Massey et al [2] found it necessary to apply a transverse saturating bias field to a YIG sensor in order to align the domains within the sample. While this technique for eliminating problems caused by domains is effective, it is not practical for many applications in which the sensor should be passive and should not itself be a source of magnetic fields.…”

An Absolute Electric Current Probe Based on the Faraday Effect

“…For slower varying currents of smaller magnitude, this type of probe can still be used by increasing the number of circuital paths either by multiple light transits or the use of multi-turu optical fibers [2,3]. Since the time resolution is limited to the light transit time between polarizers, the increase in current sensitivity is realized at the price of a longer resolution time.…”

“…The schemes [I] proposed to improve this situation, such as null-seeking feedback devices, etc., generally lead to expensive, complicated, and less than satisfactory devices. In spite of these problems, satisfactory Faraday probes for use on utility transmission lines have been realized [2,3,4].…”

Electric field sensing and imaging by noninvasive parallel-plate sensor

“…Besides electroscopes [1] and their posterity, conventional techniques to sense electric field are categorized into four groups: field meters [2,3], antennas [4], electrical probes [5], and electrooptic (EO) approaches [6,7,8,9,10]. The first and second are well-established but cumbersome, where impeded are the abovementioned simplicity, agility, and availability.…”