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This paper presents results of numerical modeling of a modified design of an optical sensor based on segmented periodic silicon oxynitride (SiON) grating evanescently coupled with silicon wire. This segmented grating works as a leaky waveguide, which filters input power from a broadband optical source and radiates it as an outcoming optical beam with both a small wavelength band and a small beam divergence. The radiation angle strongly depends on the refractive index of the grating environment and provides sensor interrogation by measuring the far field pattern in the focal plane of the lens, which is placed near the sensor element. The device concept was verified by direct numerical modeling through the finite difference time domain (FDTD) method and provided moderate intrinsic limit of detection (iLOD) ~ 0.004 RIU with a possible iLOD ~ 0.001 RIU for 10 mm-long structures. [ABSTRACT FROM AUTHOR]

The influence of high energy radiations on the performance of silicon-on-insulator photonic devices, such as straight waveguides, ring resonators and Raman lasers based on resonant microcavities, has been investigated theoretically in the near infrared. The modeling is based on a generalized full-vectorial wave equation system which also includes deep defect rate equations. Simulation results are compared with the state-of-the-art, demonstrating a very good agreement between theoretical predictions and experiments reported in literature in the case of both ionizing and nonionizing events. Moreover, a parametric analysis is presented in order to investigate the degradation mechanisms of photonic device performance that occur under the influence of radiation bombardment. [ABSTRACT FROM AUTHOR]

This paper discusses the physical nature and the numerical modeling of a novel approach of periodic structures for applications as photonic sensors. The sensing is based on the high sensitivity to the cover index change of the notch wavelength. This sensitivity is due to the effect of abnormal blocking of the guided wave propagating along the silicon wire with periodic strips overhead it through the silica buffer. The structure sensing is numerically modeled by 2D and 3D finite difference time domain (FDTD) method, taking into account the waveguide dispersion. The modeling of the long structures (more than 1000 strips) is accomplished by the 2D method of lines (MoL) with a maximal implementation of the analytical feature of the method. It is proved that the effect of abnormal blocking could be used for the construction of novel types of optical sensors. [ABSTRACT FROM AUTHOR]