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Surface enhanced Raman spectroscopy (SERS) substrate aimed at providing robust and reproducible enhancements is discussed. The periodic sinusoidal SiO 2 grating followed by silver evaporation is proposed for the creation of reproducible and effective SERS substrate based on surface plasmon polaritons (SPPs). Detailed optical properties theoretical and simulation studies with finite difference time domain (FDTD) are performed to achieve intense excitation SPPs. Substrate parameters such as period, amplitude of sinusoidal grating and thickness of silver layer, detailed excitation light parameters such as wavelength, polarization state and polarization angle are explored. It’s found that the enhancement factor (EF) of SERS is proportional to the efficiency of excitation SPPs. Optimal SERS response can be realized by assembling the substrate and excitation light parameters appropriately. The substrates are fabricated and an extra SERS effect of the optimal Ag/SiO 2 sinusoidal nanograting is demonstrated by the experiments. [ABSTRACT FROM AUTHOR]

Abstract We proposed an accurate method for simulating turbulent phase screen. Different from the subharmonic method, the low-frequency grid is not equally spaced in our method, and the distribution of sampling points can be determined by only one parameter. It is found that the accuracy of simulation depends on the distribution of sampling points, and there is an optimal distribution that minimizes the relative error between expected structure function and theoretical structure function. In order to get the optimal distribution, a search algorithm is designed. Compared with existing subharmonic method, the maximum relative error can be reduced from 10% to 0.1%, and the computation costs reduced more than two times at the same time. And compared with other methods, this method still has the advantage of precision. [ABSTRACT FROM AUTHOR]