Design and modelling of dispersion-engineered rib waveguide for ultra broadband mid-infrared supercontinuum generation

We report a dispersion-engineered As₂Se₃ chalcogenide glass rib waveguide structure for ultra broadband mid-infrared supercontinuum generation across molecular ‘fingerprint region’. The proposed rib waveguide structure offers non-linear coefficient as high as 18,250 W^?1 km^?1 at 2.5 μm. Supercontinuum spectrum spanning 2–15 μm, which not only covers the both atmospheric transparent windows (3–5 μm and 8–13 μm) in the mid-infrared domain but also covers the important molecular ‘fingerprint domain’, is obtained using only 4 mm-long rib waveguide structure. To the best of our knowledge, such broadband mid-infrared supercontinuum spectrum in As₂Se₃-based chalcogenide waveguide geometry is reported for the first time. The proposed design of rib waveguide has potential for robust, integrated and low-cost supercontinuum sources in various applications including frequency comb generation, chemical sensing, food quality control and early cancer diagnostics.     

基于Stokes矢量分析的偏光片光学参数测量

目前偏光片透过率的测量方法依赖偏光片的相对转动,受光源偏振度以及探测器偏振响应的影响大,测量精度低.为解决上述问题,本文提出了基于Stokes矢量分析的方法,通过分析入射到偏光片以及从偏光片出射的偏振光的Stokes矢量的改变,结合最优化算法来解析样品的偏振特性,从而快速、精确地测量偏光片的透过率.该方法测量速度快、可...     

Polarization characterization of biological tissues using Stokes vector decomposition

A method is proposed for characterizing the polarization properties of a depolarizing anisotropic medium based on decomposition of the Stokes vector representing the light emerging from the medium. The exiting Stokes vector can be considered as being decomposed into two parts, namely a completely unpolarized and a completely polarized part. Then, the Mueller matrix representing the sample can be extracted as a superposition of two distinguishable parts. The differential Mueller formalism is applied to one part of the Muller matrix. Here, explicit expressions are presented for the extraction of polarization properties of the medium. Results indicate that the proposed method is a promising method for characterization of complicated media such as biological tissues.     

Monte Carlo simulation of Stokes vectors of polarized light scattering from two-dimensional random rough surfaces

A Monte Carlo model was established to simulate polarized scattering fields of two-dimensional rough surfaces based on the Kirchhoff approximation. Based on this model, numerical studies of the hemispherical distribution of Stokes vectors of scattered light from dielectric and metal rough surfaces were carried out. These surfaces have Gaussian distributions with correlation length of 3.1?µm and standard deviation varying between 0.1 and 0.6?µm. The results reveal that the V component of metal surfaces has peaks antisymmetric with the incident plane, whereas the V component of dielectric surfaces is almost zero. We consider that this property of the V component would provide a new method which could be used to distinguish the target material.