采用静电纺丝法在不同气氛下制备了Sr₂MgSi₂O₇∶Eu²⁺，Eu³⁺纤维，研究其晶体结构和形貌；将纤维与聚二甲基硅氧烷（PDMS）复合后获得Sr₂MgSi₂O₇∶Eu²⁺，Eu³⁺?PDMS复合材料，研究其光致发光和应力发光性能。研究结果显示，氮气、空气下制备样品的XPS图谱同时出现Eu²⁺和Eu³⁺结合能特征峰；在360 nm和395 nm激发下复合材料的光致发光光谱中，不但有Eu²⁺位于469 nm处的蓝色宽带发射，还包含Eu³⁺位于615 nm的多个红色窄带发射。因为Eu³⁺在电荷补偿下还原成Eu²⁺并在刚性结构保护下不被氧化，证实了Eu³⁺在Sr₂MgSi₂O₇中的自还原现象。随着Eu³⁺的掺杂浓度增大，光致发光和应力发光强度都先增大后减小，Eu²⁺和Eu³⁺的发射分别在5%和10%时达到最强。应力发光强度与应力的增长是线性关系，Eu²⁺的发射增长量大于Eu³⁺。在实物照片和CIE坐标中观测到光致发光颜色从蓝色逐渐接近红色，应力发光颜色在应力增大时逐渐从粉红色变为紫粉色。该材料的研究将为发光调控提供参考，在应力传感和防伪等领域有着潜在的使用价值。

We propose a high-sensitivity bidirectional torsion sensor using a helical seven-core fiber taper embedded in multimode fiber (MHSTM). Sensors with different taper waists and helical pitches are fabricated, and their transmission spectra are obtained and analyzed. The waist and length of the sandwiched seven-core fiber are finally determined to be 68 µm and 3 mm, respectively. The experimental results show that the clockwise and counterclockwise torsion sensitivities of the proposed sensor are 2.253 nm/(rad/m) and -1.123 nm/(rad/m), respectively. When tapered waist diameter reduces to 48 µm, a superior torsion sensitivity of 5.391 nm/(rad/m) in the range of 0–4.24 nm/(rad/m) is obtained, which is 46 times as large as the traditional helical seven-core fiber structure. In addition, the MHSTM structure is also relatively stable to temperature variations.

为了探索硫系玻璃光纤器件在中红外波段超连续光源的潜在应用，自主制备了一种硫系玻璃光子晶体光纤，该光纤由组分为As₂S₃的纤芯和呈六边形排列的空气孔的包层所组成。利用波长为2.87 μm，重复频率为42 MHz，脉冲宽度为173 fs的中红外光纤激光器为泵源，利用拉锥硫系玻璃光子晶体光纤研制了中红外超连续谱。经过优化As₂S₃光子晶体光纤的拉锥直径后，其腰身直径为55 μm，长度为3 cm。在该拉锥光纤中实现了-20 dB水平的光谱覆盖范围为2 000~5 500 nm的超连续光谱，实验结果和理论计算结果一致性较好。

In this paper, a novel liquid level sensor with ultra-high sensitivity is proposed. The proposed sensor is configured by a slice-shaped composite long period fiber grating (SSC-LPFG). The SSC-LPFG is prepared by polishing two opposite sides of a composite multimode–single-mode–multimode fiber structure using a CO2 laser. The method improves the sensitivity of the sensor to external environment. Based on the simulation calculation, a liquid level sensor with a length of 3 mm is designed. The experimental transmission spectrum agrees well with the simulation result. The experimental results show that the sensitivity reaches 7080 pm/mm in the liquid level range of 0–1400 μm in water. The temperature sensitivity is 24.52 pm/°C in the range of 20°C–90°C. Due to the ultra-high sensitivity, good linearity, and compact structure, the SSC-LPFG has potential application in the field of high-precision liquid level measurement.

We propose and investigate a compact optical fiber sensor that aims to measure the torsion in both amount and direction with high sensitivity. This sensor is configured by a triangular-prism-shaped long-period fiber grating, which is fabricated by the high frequency CO2 laser polished method. The unique design of the triangular-shaped structure breaks the rotational symmetry of the optical fiber and provides high sensitivity for torsion measurement. In preliminary experiments, the torsion response of the sensor achieves a good stability and linearity. The torsion sensitivity is 0.54 nm/(rad/m), which renders the proposed structure a highly sensitive torsion sensor.

This Letter presents a new type of optical fiber probe used to detect temperature, whose structure is very simple. The optical fiber probe is filled with cholesteric liquid crystals (CLCs) whose reflected light varies with temperature. The experimental results show that the proposed sensor can achieve a temperature sensitivity of 5.64 nm/°C in the temperature range of 18–40°C. The sensor has the advantages of simple structure, low cost, and easy mass manufacture. Its size is very tiny (the tapered structure, 125 μm in maximum diameter and <300 μm in length) and it is easy to integrate and measure. Meantime, the tapered structure of the probe is also ideal for measuring small samples such as cells and microfluidic channels, which will be a promising candidate for monitoring temperature fluctuations in small spaces.

A novel phase-shifted long-period fiber grating (PS-LPFG) for the simultaneous measurement of torsion and temperature is described and experimentally demonstrated. The PS-LPFG is fabricated by inserting a pre-twisted structure into the long-period fiber grating (LPFG) written in single-mode fiber (SMF). Experimental results show that the torsion sensitivities of the two dips are ?0.114 nm/(rad/m) and ?0.069 nm/(rad/m) in the clockwise direction, and ?0.087 nm/(rad/m) and ?0.048 nm/(rad/m) in the counterclockwise direction, respectively. The temperature sensitivities of the two dips are 0.057 nm/°C and 0.051 nm/°C, respectively. The two dips of the PS-LPFG exhibit different responses to torsion and temperature. Simultaneous measurement of torsion and temperature can be implemented using a sensor. The feasibility and stabilization of simultaneous torsion and temperature measurement have been confirmed, and hence this novel PS-LPFG demonstrates potential for fiber sensing and engineering applications.

In this Letter, a dye-doped cholesteric liquid crystal (DDCLC)-filled hollow glass microsphere is demonstrated to be a resonator with good temperature response. A diglycerol layer is used to wrap the DDCLCs microdroplet to keep it steady and control its orientation. The whispering gallery mode (WGM) lasing and photonic band gap (PBG) lasing caused by two different mechanisms were obtained under the pump of a pulsed laser, and the temperature response of these two kinds of lasing was studied. For the liquid crystal and chiral material used in this Letter, both the WGM lasing and the PBG lasing have a blue shift in wavelength with increasing temperature.

A torsion sensor based on the near-helical (NH) long period fiber grating (LPFG) is fabricated by using a high frequency pulsed CO₂ laser. Each groove of the NH-LPFG is spirally written in the four sides of a single-mode fiber. The NH-LPFG has a helical periodic vertical index modulation. This is different from the screw-type index modulation of the common helical LPFGs (H-LPFGs) fabricated in a twisted fiber. The torsion and temperature characteristics of the NH-LPFG are experimentally investigated. The temperature sensitivity is about 0.0668 nm/°C. The torsion sensitivity is 0.103 nm/(rad/m) and independent of the polarization state of incident light.