An integrated photonic electric field sensor comprised of a tapered antenna array and an optical waveguide asymmetric Mach-Zehnder interferometer (MZI) has been fabricated and experimentally demonstrated. The tapered antenna array is fabricated across the MZI for a broadband receiving of the electromagnetic (EM) wave. The phase of the light beam traveling in the optical waveguide therefore changes based on the electro-optic (EO) effect of the LiNbO3 (LN) crystal, and so does the amplitude of the output end of the MZI. The packaged sensor is only 55 × 15 × 10 mm ³ in size. Experimental results reveal that the response deviation of the sensor is within ±10 dB from 100 kHz to 26.5 GHz. Moreover, the minimum detectable electric field of the sensor is 245 mV/m, and the intense nanosecond EM pulse (EMP) with peak amplitude of 25 kV/m has been detected in the time domain.

A LiNbO ₃ ‐integrated optical waveguide sensor with segmented shielding electrode are designed, fabricated and experimentally investigated. The segmented shielding electrode is designed to improve the sensor response at low frequency and simultaneously to have a larger half‐wave electric field. The minimum and maximum detectable power‐frequency electric fields of the sensor with 10 electrode elements in the time domain are 600 V/m and 139.8 kV/m, respectively, which results in a linear dynamic range of 47.3 dB. The minimum detectable electric field of the sensor with four electrode elements is 5.7 kV/m, while the maximum electric field that can be detected is more than 240 kV/m. By applying the 1.2/50 s lightning electromagnetic pulse, the frequency response of the sensor is calculated from DC to 200 kHz with variations of less than ±2 dB. All these results investigate that such sensor has potential capability to become a portable instrument for the non‐invasive measurement of intensive power‐frequency electric field in high‐voltage power system.

Integrated optical waveguide sensor has characteristics of good insulation, broadband response and small size. A LiNbO ₃ (LN) integrated optical waveguide sensor based on a dual parallel asymmetric Mach-Zehnder interferometer (DAMZI) and segmented electrode is designed, fabricated and experimentally demonstrated. By using the DAMZI with segmented electrode fabricated between the two straight waveguide arms, a push-pull modulation is generated, yielding a pair of differential signals are formed at the two outputs of the sensor. Thus based on the differential effect of the balanced photo detection (PD) at the receiving end, the noise is suppressed while the signal is enhanced. The noise floor, minimum detectable electric field, and input/output characteristics of the sensor are measured and compared with those of the sensor with single PD. Experiment results demonstrate that in comparison to the sensor with single PD, the noise floor of the sensor with balanced PD is reduced by about 6 dB while the minimum detectable electric field is reduced by about 18 dB. Besides, in the time domain, the minimum detectable electric field and dynamic range of the sensor are 12.5 V/m and 47 dB respectively. The frequency response variation is within ±1 dB from 9 kHz to 340 MHz, and the temperature stability variation is less than ±0.3 dB with the ambient temperature changed from 18 °C to 28 °C within 19 hours. All these results demonstrate that the sensor has powerful potential capability to be used for measuring the weaker electric field in the electromagnetic compatibility (EMC) area.

The three-dimensional (3D) simulation model of a lithium niobate (LiNbO₃, LN) optical waveguide (OWG) electric field sensor has been established by using the full-wave electromagnetic simulation software. The influences of the LN substrate and the packaging material on the resonance frequency of the integrated OWG electric field sensor have been simulated and analyzed. The simulation results show that the thickness of the LN substrate has a great influence on the resonant frequency of the sensor (≈33.4%). A sensor with a substrate thickness of 1 mm has been designed, fabricated, and experimentally investigated. Experimental results indicate that the measured resonance frequency is 7.5 GHz, which nearly coincides with the simulation results. Moreover, the sensor can be used for the measurement of the nanosecond electromagnetic impulse (NEMP) in the time domain from 1.29 kV/m to 100.97 kV/m.

Tea is one of the most popular drinks in the world. The rapid and accurate recognition of tea diseases is of great significance for taking targeted preventive measures. In this paper, an information entropy masked vision transformation (IEM-ViT) model was proposed for the rapid and accurate recognition of tea diseases. The information entropy weighting (IEW) method was used to calculate the IE of each segment of the image, so that the model could learn the maximum amount of knowledge and information more quickly and accurately. An asymmetric encoder–decoder architecture was used in the masked autoencoder (MAE), where the encoder operated on only a subset of visible patches and the decoder recovered the labeled masked patches, reconstructing the missing pixels for parameter sharing and data augmentation. The experimental results showed that the proposed IEM-ViT had an accuracy of 93.78% for recognizing the seven types of tea diseases. In comparison to the currently common image recognition algorithms including the ResNet18, VGG16, and VGG19, the recognition accuracy was improved by nearly 20%. Additionally, in comparison to the other six published tea disease recognition methods, the proposed IEM-ViT model could recognize more types of tea diseases and the accuracy was improved simultaneously.