Acceleration measurement is widely used in military, civil, and industrial applications. However, it is difficult for traditional microelectromechanical systems (MEMS) accelerometers to combine high sensitivity and large bandwidth. Therefore, we propose a Fabry-Perot (F-P) optomechanical accelerometer based on a suspended Si ₃ N ₄ membrane resonator. We develop an optical excitation scheme to investigate the response of the resonator and a separate laser interferometry measurement system to achieve highly sensitive displacement readout. The single thermomechanical vibration mode of the resonator enables precise conversion from displacement to acceleration. The accelerometer exhibited an acceleration sensitivity of 0.72 μg/√Hz at 412.59 kHz, reaching the thermomechanical limit. Then, we focused on studying the relationship between optical power and optical shot noise and reducing the shot noise by tuning the optical power, which increased the accelerometer’s 3 dB bandwidth by an order of magnitude from 1.56 kHz to 15.34 kHz. The displacement sensitivity of the measurement system is optimized to 2.5 fm/√Hz. This sensing platform and optical power tuning method lay a certain foundation for the development of high frequency, high sensitivity, and broadband optomechanical accelerometers.

The parity-time (PT) -symmetric gyroscope system is able to solve the problem of achieving high sensitivity in a reduced footprint for optical gyroscopes by manipulating the physical properties of the exceptional points (EP). Nevertheless, its system tuning is intricate and hard to read, which hinders its practical implementation. On the contrary, the real frequency splitting and simple tuning of the anti-parity-time(APT)-symmetric gyroscope system represents a viable alternative to the conventional PT-symmetric gyroscope. However, due to the high fabrication process required for virtual coupling, no experiments have been reported. To achieve this goal, we utilize three resonant cavities in series to construct the APT angular rate sensor system, with the assistance of lossy cavity to meet the imaginary coupling requirement. Due to the much more stable nature of resonant cavities compared to waveguides, the system has greater robustne. Simultaneously, we established the cavity photomechanics model and the angular rate sensing model of the APT system, and tested the response of the system under different frequency differences. The experiment findings demonstrate that the mode splitting in this system is 4 times greater than that of the conventional device. Additionally, the transmission spectrum amplitude displays a highly sensitive response to perturbation during the unbroken period, with a 7 times improvement compared to the first-order system. This provides the basis for experimental validation of the pioneering anti-PT gyroscope.

The bound states in the continuum (BIC) support anomalous resonances in the optical or terahertz band with a theoretically infinite quality factor. Therefore, it has great application prospects in the field of sensors. However, the current regulation of BIC mainly relies on the asymmetry of the material structure, which requires high processing technology. The structure can hardly be effectively adjusted once it is formed. In this work, we propose a new metasurface consisting of an array rectangular hole structure combined with aluminum and photosensitive silicon, which supports quasi-BIC to achieve ultrasensitive sensing in the terahertz range. By introducing photosensitive silicon, the asymmetry of the structure is efficiently controlled by the light field, thus realizing the bidirectional continuous control from quasi-BIC to BIC-like states. Through the optimization of the structure, a class of highly sensitive terahertz sensing based on optical tuning is finally proposed. The narrow-band quasi-BIC resonance is sensitive to medium thickness and refractive index, and compared with pure metal structure, the sensitivity and dynamic range can be increased by 2.60 times and 2.63 times, respectively. Due to the high slope of the Fano lineshape, sensitivity can reach 9.41 GHz/RIU and 0.65 GHz/μm, respectively. Furthermore, this feasible and practical structure provides an ideal platform for highly sensitive sensing.

The resonant fiber optic gyroscope (RFOG) driven by a broadband light source has advantages over conventional RFOGs in terms of structure, solution, etc., and provides new ideas for the commercialization of RFOGs. In this paper, the basic working principle of RFOG driven by a broadband light source is introduced. The optimal modulation coefficients are provided for sinusoidal wave modulation. The influence of the length of the fiber-optic ring resonator (FRR) and the coupling coefficient of the fiber coupler on the sensitivity is analyzed. The FRR is constructed in the over-coupled state to improve the utilization of optical power, and thus significantly increase the system sensitivity. In experiments, an RFOG prototype with a diameter of 13 cm, a height of 7 cm, and a fiber ring length of 210 m is produced. A bias instability (BI) of 0.06°/h and an angular random walk (ARW) of 0.01^∘/h are obtained.

Accurate detection of ethanol solvents plays a crucial role in food and drug safety. In this paper, a hollow microbubble resonator (HMR) based on whispering gallery mode (WGM) is designed for ethanol liquid concentration detection. To enhance the sensitivity of the sensor, MnCo ₂ O _4.5 nanomaterial is successfully modified on the inner wall of the HMR. Based on the adsorption of ethanol molecules by the porosity of MnCo ₂ O _4.5 , the effect of ethanol on the refractive index (RI) of the inner wall of the HMR is amplified. This leads to an increase in the transmission spectrum offset, improving the overall sensitivity. The sensitization mechanism is studied through simulations and experiments. The experimental results clearly demonstrate that sensitivity of the sensor coated with MnCo ₂ O _4.5 over four cycles is nearly 5 times as high as that of the uncoated sensor. Notably, in the low concentration range (0%-0.1%), the sensitivity of the sensor with MnCo ₂ O _4.5 is more than 20 times higher compared to that without MnCo ₂ O _4.5 , indicating its potential for measuring trace amounts of ethanol in water. Over an 8-day testing period conducted every 2 days, the sensor exhibited sensitivity changes of less than 10%. Additionally, the compact design and ease of manufacturing makes it a promising sensor for ethanol concentration detection.