Optical Electric Field Sensor Research Articles

Ultrasensitive optical electric field sensor with temperature compensation for point-wise and quasi-distributed sensing.

A point-wise and quasi-distributed optical sensing technique with the Vernier effect is proposed and achieved by multiplexing Fabry-Perot interferometers (FPIs). The FPIs are fabricated by LiNbO3 (LN) crystals of varying lengths to enable simultaneous measurement of electric field (E-field) and temperature. Compared to the traditional bulk-type optical E-field sensors, this innovative sensor enables E-field measurement without being limited by half-wave voltage and effectively avoids the influence of natural birefringence. By an algorithm based on the Fourier transform, sub-FPIs are addressable, and their interference spectra can be demodulated independently, where any two FPIs are paired to generate the fundamental Vernier effect (FVE) or harmonic Vernier effect (HVE). Thus, the measurement sensitivities of FPIs can be significantly improved by monitoring the spectral shift of the envelope in the superimposed spectra. The quasi-distributed sensing experiment is conducted using three cascaded FPIs, yielding E-field sensitivities of 2.84 nm/E (FVE) and 3.37 nm/E (HVE), with a standard deviation (STD) of spectrum variation after temperature compensation below 3.19 × 10-3. The proposed multiplexing method is significant for practical applications of the E-field quasi-distributed measurement.

Integrated Optical Waveguide Electric Field Sensors Based on Bismuth Germanate.

Bismuth germanate (Bi4Ge3O12, BGO) is a widely used optical sensing material with a high electro-optic coefficient, ideal for optical electric field sensors. Achieving high precision in electric field sensing requires fabricating optical waveguides on BGO. Traditional waveguide writing methods face challenges with this material. This study explores using femtosecond laser writing technology for preparing waveguides on BGO, leveraging ultrafast optical fields for superior material modification. Our experimental analysis shows that a cladding-type waveguide, written with a femtosecond laser at 200 kHz repetition frequency and 10.15 mW average power (pulse energy of 50.8 nJ), exhibits excellent light-guiding characteristics. Simulations of near-field optical intensity distribution and refractive index variations using the refractive index reconstruction method demonstrate that the refractive index modulation ensures single-mode transmission and effectively confines light to the core layer. In situ refractive index characterization confirms the feasibility of fabricating a waveguide with a refractive index reduction on BGO. The resulting waveguide has a loss per unit length of approximately 1.2 dB/cm, marking a successful fabrication. Additionally, we design an antenna electrode, analyze sensor performance indicators, and integrate a preparation process plan for the antenna electrode. This achievement establishes a solid experimental foundation for future studies on BGO crystal waveguides in electric field measurement applications.

Ultrasensitive Optical Electric Field Sensor Based on Harmonic Vernier Effect

Ultrasensitive Optical Electric Field Sensor Based on Harmonic Vernier Effect

A Linear LiNbO₃ Optical Electric Field Sensor by Twisting the Polarization Maintaining Fiber

A Linear LiNbO₃ Optical Electric Field Sensor by Twisting the Polarization Maintaining Fiber

Integrated optical electric field sensors: humidity stability mechanisms and packaging scheme

Integrated optical electric field sensors (IOES) play a crucial role in electric field measurement. This paper introduces the principles of the IOES and quantitatively evaluates the impact of humidity on measurement accuracy. Sensors with different levels of hydrophobicity coatings and hygroscopicity shells are fabricated and tested across the relative humidity (RH) range of 25%–95%. Results reveal that humidity stability is primarily influenced by water vapor absorption through the sensor shell, which increases its conductivity. This further results in amplitude deviation and phase shift of the sensor output. To address this, an optimal humidity-stable packaging scheme is proposed, which involves using PEEK shell with room temperature vulcanized fluorinated silicone rubber coating. Compared with uncoated ceramic shell, the phase shift of the IOES reduces from 90∘ to 1∘ under a RH of 90%. The amplitude deviation of electric field measurement decreases from 20% to nearly zero after a 20 h humidity experiment conducted under RH of 90% at 30 ∘C. The proposed packaging scheme could be used to improve the humidity stability of the sensors deployed in outdoor environments, especially on ships and coastal areas.

A Ti: LiNbO3 optical waveguide sensor for measurement of intensive electric field

In this paper, a Ti: LN optical waveguide intensive electric field sensor without metal structure is designed and fabricated. By using the finite element simulation, the refractive index difference Δno and Δne of the waveguide are designed as 0.0105 and 0.0305 respectively when the prediffusion depth d is 5 μm, which results in the static operating point of the sensor is 86.4° when the length L is 45 mm and the prediffusion width w is 10 μm. The simulation results show that when the design of LN substrate is 6 mm (x) × 1 mm (y) × 45 mm (z), the ratio of the external and internal electric fields is 4.216, and the half-wave electric field is 10053 kV/m. The sensor is measured by the power-frequency electric field measurement system, and the half-wave electric field is about 10135 kV/m, and the maximum detectable electric field is about 3041 kV/m.

High-frequency electric field intensity measurement based on frequency shift with high gain and wide frequency range

For the safe operation of equipment and personal safety protection in high-voltage environments, the precise measurement of the high-frequency electric field is of paramount importance. Optical electric field sensor (OES) is a current research trend for high-frequency electric field measurement but is generally limited by low sensitivity and the need for high-speed acquisition modules. Here, we propose a high-frequency electric field intensity measurement approach based on frequency shift with a high gain and a wide frequency range. We used two different frequency shift methods, i.e., stimulated Brillouin scattering and down-conversion. Based on the former method, an amplification module is designed to enhance the OES signal with a frequency range from 11 GHz to 20 GHz and a noise-suppressed gain of up to 63 dB, and based on the latter one, the high-frequency OES signal is down-converted to a sub-MHz intermediate frequency signal. The frequency shift approach shows the potential to detect and analyze high-frequency electric fields with low cost and a small footprint, which is valuable for their applications in electronic warfare, high-voltage engineering, space exploration, etc.

Temperature-Insensitive Integrated Optical Electric Field Sensor Based on Asymmetric Mach–Zehnder Interferometer

The thermal bias drift problem induces poor stability of the operating point of integrated optical electric field sensor and thus large measurement errors in the practical applications. In this article, we have proposed a passive thermal compensation approach to an inherently temperature-insensitive integrated electric field sensor. Both theoretical analysis and experiments demonstrated that the thermal bias drift could be effectively suppressed by a combination design of waveguide width and length of the asymmetric Mach–Zehnder interferometer. Based on this new waveguide design, a temperature compensated electric field sensor with optimal geometrical parameters was fabricated. Its thermal bias drift was reduced from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$-3.3^{\circ }/^{\circ }\text{C}$ </tex-math></inline-formula> to 0.23°/°C, more than ten times lower than the uncompensated conventional sensor. Furthermore, the maximum/minimum detectable electric fields are 2.5 and 200 kV/m, respectively, for measuring lighting impulse electric field, and a measurement error as low as 1.6% was achieved from 18 °C to 28 °C. These results are very encouraging for implementing practical integrated optical electric field sensing schemes.

Integrated Optical Electric Field Sensor Based on Asymmetric Mach-Zehnder Interferometer With Straight Waveguide Arms

In this paper, an asymmetric Mach-Zehnder interferometer with straight waveguide arms based integrated optical electric field sensor is proposed. Compared with the present reported integrated optical electric field sensors, the proposed sensor has relatively lower transmission loss, higher extinction ratio, much larger linear measurable range, and better thermal stability. The transmission loss of the device is demonstrated to be as low as 6 dB and the extinction ratio is as high as 35 dB. Moreover, the sensor has a linear measurable range of approximately 34 dB and the minimal detectable electric field strength of 10 V/m is achieved in the experiments. Combining the wavelength tuning technique, the thermal variations in the sensor bias have fallen from around 120 degrees down to be 2 degrees with the temperature ranging from 24°C to 70°C. These results are very encouraging toward the development of integrated optical electric field sensing systems in the practical applications.

Mathematical modeling of the parameters of an electro-optic modulator in the Mach–Zehnder interferometer configuration based on thin lithium niobate films

Subject of study. An electro-optic modulator in a Mach–Zehnder interferometer configuration based on ridge waveguides made of a thin lithium niobate film was studied. Aim of study. The study aimed to mathematically model the parameters of an electro-optic modulator in a Mach–Zehnder interferometer configuration based on ridge waveguides made of a thin lithium niobate film. Method. The dependence of the optical losses introduced by a Y-branch splitter on the angle of the splitter was investigated using a beam propagation method based on the fast Fourier transform. Main results. The results of mathematical simulation of the parameters of the electro-optic modulator in the Mach–Zehnder interferometer configuration based on thin lithium niobate films were presented. The dependence of the optical losses, introduced by the Y-splitter, on the waveguide separation angle was obtained. Images of interference patterns occurring in the output waveguide were examined. A comparison revealed that the effectiveness of the proposed interferometer configuration was higher than that of the alternative solutions available in the literature. The novelty of the results is that the configuration of the electro-optic modulator investigated in this study was fabricated in the form of an integrated optical circuit based on ridge waveguides of thin-film lithium niobate. Such a solution enables a reduction in the dimensions of the final device and increases the sensitivity compared with that of existing analogs based on bulk electro-optic crystals. Additionally, owing to the use of a semiconductor substrate, an electronic circuit can possibly be integrated into the substrate, which enables the implementation of an electro-optic sensor system on a single chip. Practical significance. The method for interference pattern analysis proposed in this study provides information on the magnitude of the voltage applied to the arm of the interferometer and enables the development of requirements for its further modernization for increasing the accuracy of measurements and developing optoelectronic devices based on thin lithium niobate films, including integrated optical electric-field sensors.

Integration of an Optical Electric Field Sensor in Lithium Niobate on Insulator

Integration of an Optical Electric Field Sensor in Lithium Niobate on Insulator

Packaging method and temperature characteristics of miniature e-field probe with fiber-lInBo 3 evanescent coupler

The fiber-waveguide evanescent coupler (FWEC) is one of the most promising directions in optical fiber sensors for electric field measurement. FWEC has extraordinary measurement performance, including millimeter-level size, high spatial resolution, broad upper limit, and free of discrete optical elements. Therefore, it has a wide range of applications, especially for very fast transient overvoltage and high electric field measurement. However, like all kinds of optical electric field sensors, the output of FWEC also shifts with temperature. Besides, the mechanical stability of FWEC is weakened as most of the cladding of D-type single-mode fiber (D-SMF) has been removed. In this paper, the FWEC sensor with stable transmission spectra is fabricated by monitoring the real-time coupling state of D-SMF and Z-cut LiNbO3. A uniform package coating of about 150 μm is formed by precisely controlling the injected QLE 1101 silicon gel. The stability test shows that the spectral distortion of packaged FWEC is only about 1.7%, indicating that the impact of packaging on the measurement performance is negligible. Through theoretical analysis and experimental verification, the peak wavelength of FWEC shifts linearly with temperature with a sensitivity of 0.08 nm/˚C. Therefore, the peak wavelength shift can be selected as the characteristic index to correct the measurement result in practical application.

The Technology of Space Electric Field Detection of Deteriorated Insulator Strings Based on Multi Rotor UAV

Porcelain insulator with good insulation performance is the key to the stable operation of power system. In order to characterize its insulation performance safely and accurately, a 1:1 three-dimensional electric field simulation model of 220 kV porcelain tension insulator string is established by using COMSOL finite element software, and a UAV live detection platform for degraded insulator string is built according to the optical electric field sensor. The results show that when the insulator deteriorates, the distribution electric field curve will appear obvious distortion; comparing the simulation results with the live measurement results, it is found that the electric field waveform curve obtained by the live detection platform of degraded insulators based on UAV can be accurate and can effectively judge the insulators with deterioration.

An optical fiber electric field sensor based on polarization-maintaining photonic crystal fiber selectively filled with liquid crystal

This paper presents a liquid crystal selective filling polarization-maintaining photonic crystal fiber (PMPCF) structure for electric field measurement. E7 liquid crystal (LC) is accurately filled into a large hole near the core of the PMPCF to form an internal fiber coupler. When an external voltage is applied, an electric field sensitivity of 1.1137 nm/Vrms is obtained. The device also responds to the frequency of the electric field, and when the frequency of the electric field increases, a blue shift of the transmitted spectrum occurs. The proposed structure has potential application value in the online measurement of electric field value and frequency.

Analysis of the detection method of insulators deterioration based on optical electric field sensors

With the acceleration of uh-voltage transmission project construction, transmission lines are becoming increasingly important to maintain the safe and stable operation of the power grid, and insulators are essential components of mechanical support and electrical connection in transmission lines. However, due to long-term environmental impact, insulators exposed deteriorate year by year. Therefore, it is necessary to detect the faulty insulator in advance, and to carry out the test in the operating state of the insulator string to identify and replace the faulty insulator string in time. However, the current method of detecting insulators in actual engineering is greatly affected by the environment, the test result is not accurate enough, the predictability is not good and the detection efficiency is low. The optical electric field sensor based on the Pockels effect of optical crystals can realize chargerd detection, improve detection accuracy, reduce environmental impact, and make the detection more stable, lower cost, better economy compared with methods widely used in the market, such as infrared detection method, ultraviolet detection method, sonic detection method, manual methods. Further consideration can be given to combining with drones to expand usage scenarios and improve detection performance for widespread use.

Design and Implementation of Integrated Optical Waveguide DC Electric Field Sensor

Design and Implementation of Integrated Optical Waveguide DC Electric Field Sensor

Online Over voltage Monitoring Method Based on Contactless Induction Technique

The operation experience and research shows that over voltage is the main factor which caused grid insulation damage in the power system, but also the main reference option of electrical equipment in insulation conditions selection. Research on system broadband transient current sensing technology based on advanced magnetic field sensors for non-contact measurement, research on system broadband over voltage sensing technology based on advanced optical electric field sensors for non-contact measurement, and development of new micro-sensing technology Distributed connection of non-contact sensing terminals, building a sensor network system for transparent sensing of transient information in substations, realizing passive and wireless communication design, realizing transparent sensing of incoming and outgoing transient information in the station, portable and easy to install, which is the transient information of the power grid Obtain analysis to provide solid data support, greatly improve the level of transient information monitoring in the substation, and improve the reliability of power grid operation.

Research and Application of Transient Transparent Sensing Technology in Substations Using Internet of Things to Distributely Connect Non-contact New Broadband Sensor

When the equipment in the substation undergoes major disturbances (such as short-circuit failure, system oscillation, frequency collapse, voltage collapse, line lightning intrusion, etc.), electrical quantities (voltage, current, frequency, etc.) will undergo transient changes. This process is to correctly analyze the accident. The basis of cause can be used to evaluate the operating status of equipment, find fault points, and quickly deal with faults. However, the current domestic transient information perception in substations still needs to be developed: 1) The existing system data sources are PT and CT data, which are restricted by the bandwidth of PT and CT, and the high-frequency monitoring accuracy is not high; 2) the construction and maintenance of centralized screens are complicated. Using a large number of secondary cables; 3) the redundancy is small, and it is not easy to increase and upgrade. Therefore, it is urgent to develop a new type of distributed substation transient information sensing technology, to develop a system wide-frequency transient current sensing technology based on advanced magnetic field sensors to achieve non-contact measurement, and to develop a system broadband transient based on advanced optical electric field sensors to achieve non-contact measurement.

Large-dynamic-range athermal lithium niobite on insulator/ TiO2 nanobeam electric field sensor

An integrated optical electric field (E-field) sensor based on a one-dimensional photonic crystal nanobeam cavity on a lithium niobite on insulator (LNOI) platform is reported here. It has a large dynamic range and extreme sensitivity. The dielectric resonant mode has a quality factor Q ≳ 105. The waveguide-coupled structure, only 25 μm long, is beneficial for future on-chip integration. The use of TiO2 compensates for the thermo-optical effect of lithium niobite (LN), while the high dielectric constant of TiO2 influences the E-field distribution. A tri-layer TiO2/LNOI/TiO2 nanobeam structure is proposed to improve electro-optical modulation efficiency in LN. Detailed analysis of noise sources shows the theoretical minimum detectable E-field to be 0.15 V m−1 with a dynamic range of 83 dB. The temperature-induced resonant wavelength variation is within 3 pm °C−1 in the range of −40 °C to 40 °C.

Transient Response of Electrostatic Field due to Collision ESD between Spherical Electrodes by using Bare-chip Optical Electric Field Sensor

Transient Response of Electrostatic Field due to Collision ESD between Spherical Electrodes by using Bare-chip Optical Electric Field Sensor