We demonstrate the single-photon Rydberg excitation of cesium atoms in a magneto-optical trap (MOT). We excite atoms directly from $6S_{1/2}$ ground state to $nP_{3/2}(n = 70 - 100)$ Rydberg state with a narrow-linewidth 319 nm ultra-violet laser. The detection of Rydberg states is performed by monitoring the reduction of fluorescence signal of the MOT as partial population on $6S_{1/2}(F = 4)$ ground state are transferred to Rydberg state. We observe clearly Autler-Townes doublet in the trap-loss spectra due to the cooling lights. Utilizing the large electric polarizibility of Rydberg atoms, we observe Stark splitting in the Autler-Townes doublet induced by background DC electric fields. We investigate the dependence of Stark shift on electric fields by theoretical analysis, and then infer the DC electric field from the measured Stark splitting. We find that there is a 44.8(4) mV/cm DC electric field in the vicinity of the cold ensemble. It indicates that high-lying Rydberg atoms can be used as sensors for DC electric fields.

The sensors capable of measuring a wide range of pressures at high temperatures are critically needed in the industrial fields. We propose an optical fiber tip probe pressure sensor based on Fabry-Pérot interferometer (FPI). This sensor is fabricated by splicing single-mode, multimode, and hollow-core fibers using arc discharge technology. Pressure is detected by demodulating the change in cavity length of the FPI. Experimental results show that the sensor's pressure sensitivity can reach −9.81 nm/MPa within a pressure range of 0–12 MPa. It maintains excellent optical properties from 20 to 1100 °C, exhibiting a temperature sensitivity of 0.33 nm/°C. To enhance pressure measurement precision at high temperatures, a fiber Bragg grating is integrated into the FPI structure for temperature sensing and error correction. The simplicity and stability of the proposed sensor make it suitable for reliable gas pressure measurements in high-temperature environments.

Fiber optic Fabry-Pérot (F-P) interferometric sensors have been widely applied in various industries, because it can sense multiple physical quantities such as pressure, vibration, and refractive index by changing its cavity length. Therefore, it is very important to get the accurate and effective cavity length information. Traditional demodulation techniques for F-P cavity suffer from low speed, high cost, and poor robustness. Here, we propose a novel ultrahigh-speed demodulation system for F-P interferometric sensors based on the spatio-temporal features of sparse spectra. This system employs a combination of a dense wavelength division multiplexer, multi-channel photodetector, and analog-to-digital converter to acquire sparse spectra at high speed. Two neural network models are trained to extract the spectral temporal and spatial features, enabling ultrahigh-speed high-resolution demodulation for the changes of the cavity length and wide-range stable demodulation for absolute cavity length. The system has a demodulation rate of up to 500 kHz and a cavity length change resolution at the nm scale. It also supports the demodulation for absolute cavity length over a wide range of 15–950 $\mu$m. And it remains stable after six hours of continuous testing. Therefore, the ultrahigh-speed wide-range demodulation system offers a novel, cost-effective, and reliable solution for engineering field, showcasing significant potential for applications in high-speed fiber optic sensing.

Fiber optic vibration sensors are widely used in industrial production, security inspection, and other fields due to the advantages of anti-electromagnetic interference, high sensitivity, and high temperature resistance. Traditional fiber optic vibration sensors can only measure a single physical quantity, so it has some shortcomings such as large measurement error and unable to self-calibration at high temperature. Here, we propose a high-temperature two-parameter fiber Bragg grating sensor for monitoring temperature and vibration signals simultaneously. Two sets of cascaded gratings are written onto a quartz fiber by using a femtosecond laser. One set of gratings is attached to a cantilever beam with a mass block to sense vibration signals. The structure of the cantilever beam is designed and optimized by theoretical calculation and finite element analysis. Another set of gratings is used to sense temperature and compensate for the effect of temperature on vibration. This sensor has a characteristic frequency of 2100 Hz and an excellent optical response from 25 to 1100°C. After temperature compensation, it has a sensitivity of 0.286 pm/g in the range of 1–50g. This work provides a new way for simultaneous detection of vibration and temperature in extreme environments, such as high temperature and strong vibration.