Temperature characteristics of Pockels electro-optic voltage sensor with double crystal compensation

Abstract

Voltage sensors based on the Pockels electro-optic effect in LiNbO 3 crystals have been applied to practical engineering measurements because of their passive nature, wide operating bands, and low transmission loss. However, the temperature of the measurement environment can greatly affect the dynamic responses of these sensors because the natural birefringence of a single LiNbO 3 crystal voltage sensor (SVS) is related to its temperature. To improve the stability of this sensor over a wide temperature range, a double crystal compensation method is introduced in this paper to compensate for the natural birefringence of the SVS. A double LiNbO 3 crystal voltage sensor (DVS) was fabricated, and its working point drift characteristics and amplitude-frequency response were investigated over the temperature range from 0 • C to 50• C. The effects of two intrinsic parameters of the LiNbO 3 crystal were also investigated. Comparison between an existing SVS and the proposed DVS showed that the DVS resisted environmental temperature fluctuations more strongly. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Real-Time Polarimetric Optical High-Voltage Sensor Using Phase-Controlled Demodulation

“…The total phase shift between the ordinary and extraordinary waves propagating though the OPM is sum of an electro-optic phase shift Φ(t), induced by V m (t), and a quasi-static phase shift Φ 0 (t), caused by the natural birefringence of the crystal [4]. According to [8], Φ 0 (t) varies slowly in time in a random way, and this variation is up to five orders of magnitude greater than that caused by Φ(t). Following [4], the OPM theoretical half-wave voltage can be calculated as V π m = 64.92 V. This relatively small value of V π m provides the OPM cell with the capability to realize electronic adjustments to compensate the fading effect at the HVS cell output due to environmental drifts.…”

“…When the LiNbO 3 Pockels cell exhibits natural birefringence, the OVS becomes highly sensitive to variations in ambient temperature. In order to solve this drawback, a passive compensation arrangement, called double-crystal configuration, consisting of two identical cascaded cells with a λ/2 waveplate sandwiched between them was proposed [8].…”

Compensation of Frequency Drift in Frequency-Sweep Polarization-Modulation Ranging System

“…However, in the FSPM ranging system, the frequency is vulnerable to phase delay variation due to the sensitivity of crystals (e.g., LiNbO3) in the electrooptic modulator (EOM) to temperature disturbance. The heat dissipation of electronic components and laser irradiation will accelerate the temperature variation [24], thus leading to distance measurement errors. In order to investigate this problem, a theoretical model was developed for the FSPM ranging systems.…”

“…An example of this is connecting a compensate crystal that has the same size and performance with the modulate crystal, with the optical axes of the crystals perpendicular to each other so that the phase delay in the two identical crystals are complementary [26]. Another way is to make the two crystals in series, with one half-wave plate placed in the middle of them to make the polarization plane of the polarized light rotate by λ/2 [24]. In these methods, crystals with exactly the same parameters and their perfect assembly are the key to compensation, but that is difficult to achieve.…”

Polarimetric Optical High-Voltage Sensor Using Synthetic-Heterodyne Demodulation and Hilbert Transform With Gain Control Feedback

“…Temperature variations can affect the detected laser power and the interferometer visibility; however the method is selfcalibrated and independent of ambient fluctuations that affect the product AV. [24].…”