This paper presents AlScN piezoelectric two-axis MEMS mirrors with gimbal-less and gimbaled designs fabricated in a CMOS-compatible manner. Integrated piezoelectric sensors provided feedback signals of the actual mirror positions. The mirror with a diameter of 1.5 mm possessed adjustable optical tilt angles of up to 22.6° @ 30 V, with a high resonance frequency of about 8.2 kHz, while the 3 mm mirror reached 48.5° @ 41 V. The mirror with the gimbaled structure exhibited an excellent field of view and good mechanical decoupling. Additionally, a significant improvement in mirror scanning performance was observed in a vacuum (4 Pa), proving that the optical field of view was magnified by more than a factor of 10.

Miniaturization is a trend of development toward practical applications for diamond nitrogen-vacancy centers-based sensors. We demonstrate a compact diamond magnetic field sensor device using a standard microfabrication process. A single-crystal-diamond plate is embedded in a cavity formed with stacking of three silicon chips. Thermal compression bonding is implemented at silicon–silicon and diamond–silicon interfaces ensuring mechanical robustness. The specific construction volume for the essential sensor component is about 10 × 10 × 1.5 mm³. By integrating a gradient index lens pigtailed fiber to the sensor device, 532-nm laser light and emitted fluorescence share a common path for excitation and detection. An omega-shaped transmission line for applied microwave power is fabricated directly on the surface of diamond. The integrated sensor device exhibits an optimized sensitivity of 2.03 nT·Hz^−1/2 and over twofold enhancement of fluorescence collection efficiency compared to bare diamond. Such a sensor is utilized to measure a magnetic field change caused by switching a household electrical appliance.

Accurate and efficient measurements of the piezoelectric properties of AlN and AlScN films are very important for the design and simulation of micro-electro-mechanical system (MEMS) sensors and actuator devices. In this study, a process control monitor (PCM) structure compatible with the device manufacturing process is designed to achieve accurate determination of the piezoelectric coefficients of MEMS devices. Double-beam laser interferometry (DBLI) and laser Doppler vibrometry (LDV) measurements are applied and combined with finite element method (FEM) simulations, and values of the piezoelectric parameters d₃₃ and d₃₁ are simultaneously extracted. The accuracy of d₃₁ is verified directly by using a cantilever structure, and the accuracy of d₃₃ is verified by in situ synchrotron radiation X-ray diffraction; the comparisons confirm the viability of the results obtained by the novel combination of LDV, DBLI and FEM techniques in this study.

This paper presents a compact and high-performance piezoelectric micro-electro-mechanical system (MEMS) fast steering mirror (FSM) designed for use in laser inter-satellite links (ISLs). The FSM features a large optical aperture of 10 mm and is batch fabricated using an 8-inch wafer-level eutectic bonding process, packaged into a volume of 26 × 22 × 3 mm³. Notably, the piezoresistive (PZR) sensor is integrated on the spring of the FSM to facilitate precise beam control. Furthermore, an intermediate directional defect structure is novelly designed to create a Stress Concentration Region (SCR), effectively improving PZR sensitivity from 3.3 mV/(V∙mrad) to 5.4 mV/(V∙mrad). In this article, various performance metrics of the FSM are tested, including the mechanical characteristics, PZR sensor properties, and mirror optical quality, which all meet the requirements for laser ISLs. Results indicate that the FSM achieves a high resonant frequency (>1 kHz) and a low nonlinearity of 0.05%@ ± 2.1 mrad. A remarkable minimum angular resolution of 0.3 μrad and a repeated positioning accuracy of 1.11 μrad ensure exceptional pointing precision. The open-loop control is driven by the double-step algorithm, resulting in a step response time of 0.41 ms and achieving a control bandwidth over 2 kHz. Additionally, the integrated angular sensor demonstrates a nonlinearity of 0.09%@ ± 1.05 mrad, a sensitivity of 5.1 mV/(V∙mrad), and a minimum angular resolution of 0.3 μrad. Under quasi-static driven conditions (500 Hz @ ± 2 mrad), the maximum dynamic deformation of the mirror surface is merely 2 nm.

We present a new magnetometry method integrating an ensemble of nitrogen-vacancy (NV) centers in a single-crystal diamond with an extended dynamic range for monitoring a fast changing magnetic-field. The NV-center spin resonance frequency is tracked using a closed-loop frequency locked technique with fast frequency hopping to achieve a 10 kHz measurement bandwidth, thus allowing for the detection of fast changing magnetic signals up to 0.723 T/s. This technique exhibits an extended dynamic range subjected to the working bandwidth of the microwave source. This extended dynamic range can reach up to 4.3 mT, which is 86 times broader than the intrinsic dynamic range. The essential components for NV spin control and signal processing, such as signal generation, microwave frequency control, data processing, and readout, are integrated in a board-level system. With this platform, we demonstrate a broadband magnetometry with an optimized sensitivity of 4.2 nT Hz^−1/2. This magnetometry method has the potential to be implemented in a multichannel frequency locked vector magnetometer suitable for a wide range of practical applications, such as magnetocardiography and high-precision current sensors.

Magnetic field sensors based on quantum effects have shown superior performance in sensitivity, wherein the nitrogen-vacancy center in diamond has emerged as a microfabrication compatible solid-state platform for measuring magnetic fields at room temperature. Here, a closed-loop current sensor based on a compact diamond sensor is presented. Adapting dual-frequency driving mode and magnetic balance approach, a magnetic-temperature dual-loop architecture is established to extend the dynamic range and suppress the temperature drift, simultaneously. The proposed current sensor demonstrates an accuracy of 0.061% at a measuring range of ±1000 A. An isolation factor of 30.3 dB for temperature against magnetic field is obtained via the dual-loop calibration. The closed-loop strategy permits rapid adjustment of the output signal to align with fluctuations in the primary current and the response speed is achieved up to 107.6 kA·s ^-1 . Our proposed closed-loop current sensor has potential applications in power grid and electric vehicle monitoring systems.