In this paper, a high-fineness fiber-optic Fabry–Perot high-temperature pressure sensor, based on MEMS technology, is proposed and experimentally verified. The Faber–Perot cavity of the pressure sensor is formed by the anodic bonding of a sensitive silicon diaphragm and a Pyrex glass; a high-fineness interference signal is obtained by coating the interface surface with a high-reflection film, so as to simplify the signal demodulation system. The experimental results show that the pressure sensitivity of this sensor is 55.468 nm/MPa, and the temperature coefficient is 0.01859 nm/°C at 25~300 °C. The fiber-optic pressure sensor has the following advantages: high fineness, high temperature tolerance, high consistency and simple demodulation, resulting in a wide application prospect in the field of high-temperature pressure testing.

This paper presents and experimentally demonstrates an all-quartz fiber-optic Fabry–Pérot (FP) high-temperature pressure sensor with interference signal enhancement based on micro-electro-mechanical system (MEMS) technology. By incorporating a nanoforest array and an optical microsphere lens, the quality of the optical interference signal generated by the multilayer fiber-optic FP sensing structure is effectively enhanced. MEMS fabrication and high-temperature bonding techniques are employed to enable batch fabrication of the sensing units, while laser fusion splicing is utilized to achieve adhesive-free packaging and integration of the sensor with high-temperature-resistant optical fibers. Experimental results demonstrate that the fabricated all-quartz fiber-optic FP high-temperature pressure sensor enables stable pressure measurements over a range of 0–200 kPa within a temperature range of 20–700 °C. At room temperature, the sensor exhibits a pressure sensitivity of 56.6 nm/kPa and a maximum nonlinearity error of 0.49% F.S. In addition, the sensor maintains good operational stability under high-temperature conditions. Owing to its all-quartz structure, the proposed sensor offers excellent high-temperature resistance, good temperature stability, and strong potential for batch fabrication, providing a viable approach for the development and application of fiber-optic pressure sensors in high-temperature environments.

To address the demand for underwater acoustic detection with hydrostatic pressure resistance, this paper proposes a fiber-optic Fabry–Perot (F-P) underwater acoustic sensor based on micro-electromechanical system (MEMS) technology. According to the F-P interference principle, the diaphragm deforms under acoustic pressure, inducing variations in the F-P cavity length which modulate the interference spectrum and enable the measurement of underwater acoustic signals. A sensing diaphragm with a composite structure consisting of a central boss and a micro-hole array is designed, which improves the optical signal quality while reducing the influence of the pressure difference between the inner and outer surfaces of the diaphragm on sensor operation. MEMS fabrication, computer numerical control (CNC) machining, and laser fusion splicing technologies are employed to achieve batch fabrication of the sensing units and adhesive-free integration of the sensor. Experimental results show that the proposed sensor exhibits a flat frequency response within ±1.5 dB over the range of 1 kHz to 10 kHz, with an average signal-to-noise ratio (SNR) of 86.35 dB. The sensitivity reaches −181.79 dB re 1 rad/μPa at 10 kHz, with a maximum nonlinearity of 0.48% F.S., a repeatability error of 0.15% F.S. and a dynamic range of 100.83 dB. The proposed sensor features miniaturization, high consistency, hydrostatic pressure self-balancing capability, and immunity to electromagnetic interference, providing a solid foundation for hydrostatic-pressure-resistant underwater acoustic measurements in deep-sea environments.

Conventional fabrication methods for fiber Bragg grating (FBG) struggle to simultaneously enhance the bandwidth and the side mode suppression ratio (SMSR), which limits their applications in photonic systems and sensing systems. We propose a femtosecond laser edge-constrained composite apodization method for simultaneously enhancing the bandwidth and SMSR of FBGs. Building on the multi-layer composite apodization technique, this method simultaneously controls the position and length of the writing lines to constrain the coupling strength at both edges of the FBG, thereby expanding bandwidth while improving SMSR. The writing results show that, compared with the unconstrained case, the SMSR of the edge-constrained composite apodized FBG (ECAFBG) improves by approximately 4.7 dB while maintaining an essentially unchanged bandwidth of 3.7 nm and undegraded reflectivity, with a length of only 0.7 mm. Dynamic strain and intensity demodulation is applied to the ECAFBG. The results demonstrate that the ECAFBG is capable of dynamic strain measurement over a relatively large range. The proposed method provides an effective approach to simultaneously achieve short-length FBGs with wide bandwidth and high SMSR and has potential applications in compact laser and sensing devices.