In-plane ESPI using an achromatic interferometer with low-coherence laser source

The use of an achromatic interferometer is explored as a means of doing in-plane ESPI measurements using a laser diode as the light source. This interferometer type, which uses a diffraction grating in place of the conventional beamsplitter, has two features that make it suitable for making ESPI measurements over extended areas, even when using a low-coherence laser diode source. First, the parallelogram optical geometry of the interferometer causes all rays passing through to have the same optical path lengths. Second, the interferometer is achromatic, whereby the piezo-actuated mirror that steps the illumination light does so by the same phase angle, independent of wavelength. This latter feature accommodates the spectral impurity of a laser diode source. A periodic variation of fringe visibility is observed in experiments, where narrow ranges of high visibility occur at regular spatial intervals. This behavior derives from the clustered discrete spectral character of laser diode light output. A method to “tune” the interferometer by slightly rotating the diffraction grating is described so as to achieve consistent high fringe visibility throughout the measured images.     

Upgrade of beamline BL08B at Taiwan Light Source from a photon‐BPM to a double‐grating SGM beamline

During the last 20 years, beamline BL08B has been upgraded step by step from a photon beam‐position monitor (BPM) to a testing beamline and a single‐grating beamline that enables experiments to record X‐ray photo‐emission spectra (XPS) and X‐ray absorption spectra (XAS) for research in solar physics, organic semiconductor materials and spinel oxides, with soft X‐ray photon energies in the range 300–1000 eV. Demands for photon energy to extend to the extreme ultraviolet region for applications in nano‐fabrication and topological thin films are increasing. The basic spherical‐grating monochromator beamline was again upgraded by adding a second grating that delivers photons of energy from 80 to 420 eV. Four end‐stations were designed for experiments with XPS, XAS, interstellar photoprocess systems (IPS) and extreme‐ultraviolet lithography (EUVL) in the scheduled beam time. The data from these experiments show a large count rate in core levels probed and excellent statistics on background normalization in the L‐edge adsorption spectrum.     

980nm半导体激光器输出光谱特性的改善

为了改善980nm半导体激光器的输出光谱特性,采用传输矩阵分析法推导了双布喇格光纤光栅谐振腔的传输表达式,对布喇格光纤光栅长度和谐振腔腔长对输出光谱的影响进行模拟仿真,结果表明布喇格光纤光栅长度对输出光谱的影响大于谐振腔腔长对输出光谱的影响,加长布喇格光纤光栅长度能压缩输出光谱线宽.在980nm半导体激光器尾纤上写入不同布喇格光纤光栅长度的双布喇格光纤光栅谐振腔,验证了引入双布喇格光纤光栅谐振腔在压缩980nm半导体激光器输出光谱线宽的同时改善了其输出光谱的稳定性.当环境温度在0~75℃范围内变化时,980nm半导体激光器输出中心波长仅变化0.06nm.     

基于光楔阵列产生光学涡旋阵列的研究

在研究光楔衍射法产生单涡旋的基础上,基于长条形光楔阵列,提出了利用光束阵列衍射产生涡旋阵列的方法.该方法要求光束阵列在平行于光楔边缘方向上的光束间距等于光束直径的整数倍.利用超精密机床采用一体化加工法加工了光楔阵列元件,验证了该方法的可行性.利用空间光调制器快速灵活调整光束阵列的优点,搭建了借助空间光调制器加载达曼光栅衍射产生所需光束阵列的实验光学系统.针对光束阵列与光楔阵列的匹配问题,研究了达曼光栅掩模图基本单元对光束阵列的调控,获得了可调结构的光束阵列.实验产生了拓扑荷一致的光学涡旋阵列,与仿真结果相一致,证明所提方法的有效性.     

Low power Electro-optical filter: Constructed using silicon nanobeam resonator and PIN junction

In this paper, a high tunable Electro-optical filter is designed and simulated with low electric power consumption. A silicon nanobeam resonator based on one-dimensional photonic crystal in the form of Fabry–Perot structure, silicon-on-insulator waveguide, is proposed with a PIN junction. In designing nanobeam resonator, “deterministic design method” is used to achieve the high quality factor and high-transmission rate. Tuning of the resonant wavelength in the output channel of the filter is achieved by manipulating the refractive index of the active area by using the free-carrier dispersion effect. The output wavelengths of designed device can be tuned for the telecom-friendly 1.55 µm range. The device shows a wavelength shift higher than 3 nm for a power consumption of only 0.9 mW. Finally, the simulation results show that the provided device can be considered as a narrowband and tunable Electro-optical filter that is suitable for DWDM communication system.     

光栅投影相位法系统模型及标定方法

本文针对传统投影光栅相位法的光学三角法模型进行了改进,采用直入射光路并配合使用一种简便易行的标定方法,只需使用相移公式求取相位差,而不会引入与系统几何位置关系有关的量,简化了求取高度矩阵的要求。实验结果表明,新系统模型精度良好,测量误差为0.107 mm。采用该模型和标定方法可以克服传统方法系统模型的局限性,最大限度减少误差源并提高抗干扰性。     

Amphibious sensor of temperature and refractive index based on D-shaped photonic crystal fibre filled with liquid crystal

ABSTRACT

A D-shaped photonic crystal fibre filled with liquid crystal was demonstrated as an amphibious sensor for detection of both temperature and refractive index, when combined with plasma materials. Specifically, the optical component is implanted into a complete optical system ensuring modulation of the external electric field. When the refractive index of the external solution changes from 1.0 to 1.6, the y-polarised mode has a loss spectrum with a wavelength sensitivity of up to 2275 nm/RIU, and the corresponding amplitude sensitivity is ?88.2RIU^?1. When the perceived temperature changes from 15°C to 50°C, the temperature of the sensor is correspondingly expressed as the maximum wavelength sensitivity of 9.09 nm/°C and the amplitude sensitivity of ?0.311°C^?1. In addition, the actual micro-operation processes have been studied in detail, such as polishing depth, coating thickness and coating method. This provides practical ideas for real-time sensing analysis that requires harsh environments.     

Templated‐Assembly of CsPbBr3 Perovskite Nanocrystals into 2D Photonic Supercrystals with Amplified Spontaneous Emission

Perovskite nanocrystals (NCs) have revolutionized optoelectronic devices because of their versatile optical properties. However, controlling and extending these functionalities often requires a light‐management strategy involving additional processing steps. Herein, we introduce a simple approach to shape perovskite nanocrystals (NC) into photonic architectures that provide light management by directly shaping the active material. Pre‐patterned polydimethylsiloxane (PDMS) templates are used for the template‐induced self‐assembly of 10 nm CsPbBr₃ perovskite NC colloids into large area (1 cm²) 2D photonic crystals with tunable lattice spacing, ranging from 400 nm up to several microns. The photonic crystal arrangement facilitates efficient light coupling to the nanocrystal layer, thereby increasing the electric field intensity within the perovskite film. As a result, CsPbBr₃ 2D photonic crystals show amplified spontaneous emission (ASE) under lower optical excitation fluences in the near‐IR, in contrast to equivalent flat NC films prepared using the same colloidal ink. This improvement is attributed to the enhanced multi‐photon absorption caused by light trapping in the photonic crystal.     

Non‐Lithography Hydrodynamic Printing of Micro/Nanostructures on Curved Surfaces

A key issue of micro/nano devices is how to integrate micro/nanostructures with specified chemical components onto various curved surfaces. Hydrodynamic printing of micro/nanostructures on three‐dimensional curved surfaces is achieved with a strategy that combines template‐induced hydrodynamic printing and self‐assembly of nanoparticles (NPs). Non‐lithography flexible wall‐shaped templates are replicated with microscale features by dicing a trench‐shaped silicon wafer. Arising from the capillary pumped function between the template and curved substrates, NPs in the colloidal suspension self‐assemble into close‐packed micro/nanostructures without a gravity effect. Theoretical analysis with the lattice Boltzmann model reveals the fundamental principles of the hydrodynamic assembly process. Spiral linear structures achieved by two kinds of fluorescent NPs show non‐interfering photoluminescence properties, while the waveguide and photoluminescence are confirmed in 3D curved space. The printed multiconstituent micro/nanostructures with single‐NP resolution may serve as a general platform for optoelectronics beyond flat surfaces.