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Nonlocal observables of spacelike separated quantum systems in combination with their measurements contribute greatly to quantum theory and its applications. We present a nonlocal generalized quantum measurement protocol for measuring product observables, assisted by a meter in a mixed entangled state rather than maximally or partially entangled pure states. By tuning the entanglement of the meter, measurement strength of arbitrary values can be achieved for nonlocal product observables, since measurement strength equals the concurrence of the meter. Furthermore, we present a specific scheme to measure the polarization of two nonlocal photons using linear optics. We refer to the polarization and spatial-mode degrees of freedom of the same photon pair as the system and the meter, respectively, which significantly simplifies the interaction between the system and the meter. This protocol can be useful for applications involving nonlocal product observables and nonlocal weak values, and for tests of quantum foundations in nonlocal scenarios.

A sapphire fiber high-temperature vibration sensor with an extrinsic Fabry-Perot interferometer (EFPI) structure is proposed and experimentally demonstrated. The vibrating diaphragm of the sensor is a supported beam structure fabricated by etching a single-side polished sapphire wafer using a femtosecond laser. The FP cavity of the sensor is composed of the sapphire fiber end face and the polished surface of the vibrating diaphragm. The interference signal of the sensor is picked up by the sapphire fiber and transmitted to a laser interferometry demodulator through a multimode fiber. Experimental results show that the acceleration response is linear in the range of 0-10 g along with an acceleration sensitivity of 20.91 nm/g. The resonance frequency of the sensor is 2700 Hz, which is consistent with the ANSYS simulation results. The sensor can also work in the temperature range from room temperature to 1500 ℃, providing a feasible method for vibration measurements in high-temperature environments.

With ultrashort pulse durations and ultrahigh peak intensities, ultrafast lasers can create different types of micro/nano-structures to functionalize the processed surface with new properties. However, the applications of this method on freeform surfaces are still limited by the short length of a laser focusing spot and complex control of the 3D moving trajectory in the fabrication process. In this paper, we overcome this problem by shaping the on-axis intensity along the propagation axis using the spatial light modulator. By designing the phase mask, we increased the length of the stable-intensity zone (intensity fluctuation < 10%) by more than 3 times compared to that of an unshaped Bessel beam. The energy deposition was also optimized to be less than 2% fluctuation based on simulations. Using this method, we fabricated micro/nano structures on 3D surfaces at different fluences and demonstrated various properties including colorization, anti-reflection, and hydrophobicity in large height range. We demonstrated the applications of the proposed method in creating hydrophobicity on complex freeform syringe tip surfaces. This improved the minimum manipulatable volume of a liquid droplet to 2 times smaller compared with untreated syringe, thus greatly extending its performance for micro-droplet manipulation. This method offers an alternative approach for reliable and affordable freeform curved-surface processing.

Metal surfaces with low reflectance have received considerable attention for their great optical, electrical, and thermal properties. However, the difficulty in achieving low reflectance on curved metal surfaces has hindered their practical applications. We propose a rapid and flexible method for processing a three-dimensional surface with antireflective properties. A Bessel beam created using an axicon is employed to generate ripple structures on the curved surface, thereby assisting subsequent thermal oxidation. Ripple structures coated with oxide semiconductor nanowires are then processed on a Cu substrate, thus further reducing reflectance. Antireflective properties with a minimum reflectance of less than 0.015 at a wavelength of 500–1200 nm could be achieved by using this method. This presented approach reduces dimensionality in laser processing, subsequently improving processing efficiency, and provides a foundation for the practical application of metal antireflective surfaces.

We achieved the controllable formation of laser-induced periodic surface structures (LIPSSs) on ZnO films deposited on fused silica induced by modulated temporally shaped femtosecond (fs) laser pulses (800 nm, 50 fs, 1 kHz) through the laser scanning technique. Two-dimensional (2D) high spatial frequency LIPSSs (HSFLs) with a period from 100 to 200 nm could be flexibly modulated based on the preprocessed nanostructures with appropriate fs laser irradiation conditions (fluence, scanning speed, and pulse delay). The finite-difference time-domain (FDTD) method combined with the Drude model was employed to calculate the redistributions of electric fields, which suggested the origin of HSFL formation.

A compact optical fiber sensor for simultaneous measurement of strain and temperature is designed and experimentally investigated. The proposed sensor consists of a two-peanut-taper Mach-Zehnder interferometer (MZI) and in-line embedded fiber Bragg grating (FBG). The sensor at a length of 35 mm presents strain sensitivities 1.07 pm/με and 0.891 pm/με, the temperature sensitivities are 55.35 pm/°C and 10.85 pm/°C, for MZI and FBG, respectively. Through tapering the center of the sensor by a fusion splicer, the strain sensitivity of the MZI is improved to 1.93 pm/με. The resolutions for strain and temperature measurement are ±3.104 με and ±0.194°C with the wavelength resolution of 5 pm. The experimental results show that the sensor is able to simultaneously measure strain and temperature by sensitivity matrix with advantages such as simple structure, compact size, ease of fabrication, low cost, etc.