A novel whispering gallery mode (WGM) strain sensor based on microtube has been proposed, where perceiving strain variations are reported via the dynamical regulation of a whispering gallery mode. The WGMs in the microtube resonator were evanescently excited by a micro-nano fiber fabricated by the fusion taper technique. The structural changes of microtubes under axial strain were simulated with finite element software, and the effect of microtube wall thickness on strain sensitivity was systematically studied through experiments. The experimental results show that the strain sensitivity of thin-walled microtube is found to be 1.18 pm/με and the Q-factor in the order of 4.4×10⁴. Due to its simple fabrication and easy manipulation as well as good sensing performance, the microtube strain sensor has potential applications in high-sensitivity optical sensing.

Theoretical design of a neotype fluidic controlling sensor system based on side-polished optical fiber is proposed. Numerical investigations demonstrate that the higher birefringence and resonance coupling can be achieved by flexible design of the polishing shape and depth in the research wavelength. The fluidic system is beneficial to selective integration of functional materials. The material is integrated into the fluidic system, which can achieve a birefringence up to 6.98×10^-5, and the application of Sagnac thermometer in temperature sensing is studied, and a group of dips with different temperature sensitivities would be observed in the transmission spectra, which is about 1.6 nm/°C by calculating. furthermore, by introducing resonant coupling, single mode single polarization at 1 310 nm is realized. The refractive index (RI) response of the sensing system for a low RI range of 1.39—1.37 is approximately linear, and exhibits a sensitivity of 6 338 nm/RIU. The results show that the proposed neotype fluidic controlling system can be used as a flexible polarization filter or as a potential two-parameter sensor.

A temperature-insensitive polarization filter and a neotype sensor based on a hybrid-circular-hole microstructured op-tical fiber (MOF) are proposed. Numerical investigations demonstrate that the x polarized component of silica core mode can couple to the cladding mode in the researched wavelength, while the y polarized component would not. Fur-thermore, the resonant region can be controlled by changing the diameters or coordinates of the air holes, and the MOF has good performance on stability of temperature. Moreover, the hybrid-circular-hole structure is propitious to selec-tively integrate different functional materials. Two different materials are integrated into this proposed MOF, the ap-plication of the Sagnac interferometer in temperature sensing is studied, and two groups of dips would be observed in the transmission spectra, which have different temperature sensitivities. Therefore, the proposed MOF can be used as a flexible temperature-insensitive polarization filter or potentially applied to a two-parameter sensor.

报道了一种利用激光二极管(LD)双端面泵浦的Nd∶YAG激光晶体, Cr4+∶YAG晶体被动调Q, LBO临界相位匹配腔内倍频的高转换效率的绿光激光器。分析了双端面泵浦YAG激光器的热效应, 实验中LD双端面泵浦, 采用U型平行平面腔结构对Nd∶YAG进行传导冷却。 当总泵浦光为33.8 W时, 得到被动调Q频率10 KHz、功率8.21 W的线偏振基频光输出。6.72 W的绿光输出的倍频效率为86%, 输出光束为基模, M2为1.4。实验表明双端面泵浦YAG倍频激光器具有很高的转换效率。