Fiber Optic Electric Field Sensor Research Articles

Computer simulation of the fiber optic electric field sensor

The article describes an approach for simulating the fiber optic electric field sensor with a sensitive element operating on the Pockels effect arising in an optical waveguide recorded in a lithium niobate crystal. The sensor simulating was implemented in the NI LabVIEW programming environment and built using a mathematical apparatus based on the formalism of Jones matrices, which allowed to describe the polarization state of the light beam at the output of the sensor and to calculate the intensity of the interference signal at the photodetector input. Besides, additional modulation with a sawtooth signal and digital phase detection were used in the simulation. The sensor model described in the article can be easily modified and complicated, which makes it possible to use it for research and analysis of both parasitic effects and different optical sensor configurations.

Optical Sensing of Electric Fields in Harsh Environments

Fiber optic electric field sensors are ideal for characterizing the electric field in many different systems. Unfortunately, many of these systems produce one or more noise types, like vibrational noise which contribute to a harsh sensing environment on the fiber optic sensor. When fiber optic sensors are placed in a harsh vibration environment, multiple noise types can overwhelm the measurements. This work shows how to simultaneously eliminate three different noise types in a fiber optic sensor induced by a harsh vibration environment. Specifically, nonlocalized vibration-induced interferometric noise is up converted to higher frequency bands by single-tone phase modulation. Then, localized vibrational noise, and radio frequency noise are all eliminated using a push–pull slab coupled optical sensor configuration to allow for an optical measurement of an electric field in a harsh environment.

High electric field measurement using slab-coupled optical sensors.

A fiber-optic electric field sensor was developed to measure electric field up to 18MV/m. The sensor uses resonant coupling between an optical fiber and a nonlinear electro-optical crystal. The sensing system uses high dielectric strength materials to eliminate dielectric breakdown. A postprocessing nonlinear calibration method is developed that maps voltage change to wavelength shift and then converts the wavelength shift to electric field using the transmission spectrum. The nonlinear calibration method is compared against the linear method with electric field pulses having magnitudes from 1.5 to 18MV/m.

Push-pull slab coupled optical sensor for measuring electric fields in a vibrational environment.

Vibration-insensitive fiber optic electric field sensor is created by fabricating two sensing elements in close proximity onto the same optical fiber and subtracting the two signals. The device is used to measure an electric field of 10 kV/m, while the sensor is being bent and impacted.

Fiber-Optic Electric Field Sensor Based on Electrostriction Effect

This paper presents a new method for measuring AC field strength, with application of electrostriction effect of electrostrictive ceramics and technology of fiber Bragg grating. We use electrostriction effect to design the fiber-optic electric field sensor. This device turns the strain of electrostriction material influenced by electric field into the strain of fiber Bragg grating, then wavelength of feedback changes. We can get the strain of electrostriction material through the comparison between initial wavelength and wavelength of feedback, then measurement of electric field strength can be achieved by detecting the strain of electrostriction material. Experiments indicate that fiber-optic electric field sensor based on electrostriction effect is of effective value for measuring electric field strength, and the response of measuring system to AC electric field is linear. We apply an effective method for the research of measuring electric field strength.

Microring Resonators Made in Poled and Unpoled Chromophore-Containing Polymers for Optical Communication and Sensors

Poled and unpoled chromophore-containing polymers offer some unique advantages in device functionality and fabrication. UV light and electron beam (e-beam) can bleach out the color of chromophores and reduce the index of refraction of the polymer. The photobleaching and e-beam bleaching methods form optical waveguides in a single step and do not involve solvents or wet chemicals, and can be applied to polymers that are not compatible with other waveguide fabrication techniques. A variety of microring resonator devices for fiber-optic telecommunication and sensors have been realized with chromophore-containing polymers. A novel broadband fiber-optic electric field sensor is presented as an example. The sensor uses a polymer with chromophores preferentially aligned after electric poling, and the microring resonator is directly coupled to the core of optical fiber. The feasibility of vertical integration of a poled electrooptic polymer waveguide device interfaced with silicon microelectronic circuits is also demonstrated.

Fiber optic electric field sensors using polymer-dispersed liquid crystal coatings and evanescent field interactions

We report a simple evanescent field fiber optic electric field sensor constructed by coating the exposed fiber optic core with a polymer-dispersed liquid crystal (PDLC). It is well known that the effective refractive index of the liquid-crystal polymers has a large dependence on the direction and the magnitude of an applied electric field. This dependence was large enough in our devices to enable simple transmission measurements to detect the presence of an applied electric field across the fiber optic. The sensors showed good sensitivity and reproducibility with its response dominated by the RC time constant of the structure rather than the response of the PDLC. Its response time was approximately 3 min with 15–20 min relaxation time. Using an electric circuit model of the device, we also discuss how the sensor's response time can be improved by many orders of magnitude.