Concept of Optical Sensor Utilising the Far Field Pattern Radiated by Periodic Grating Strips Over Silica Cladding on the Silicon Wire Waveguide

摘要

This paper describes the novel concept of the optical sensor, which utilizes the physical nature of the light propagating in a silicon wire with the periodic segmented grating placed in the waveguide vicinity over the silica buffer. In specific cases, this segmented grating works as a virtual leaky waveguide, which radiates power as an outcoming optical beam having small both wavelength band and beam divergence, The radiation angle strongly depends on the refractive index of the grating environment. Thus, this device can be used as an optical sensor with the readout to be arranged by measuring the far field pattern in the focal plate of the lens, which is placed near the sensor element The device concept is verified by direct numerical modelling through the Finite Difference Time Domain (FDTD) method.