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oai:docta.ucm.es:20.500.14352/510402024-08-23T16:53:10Zcom_20.500.14352_14col_20.500.14352_15

00925njm 22002777a 4500 dc Rodrigo Martín-Romo, José Augusto author Cheben, Pavel author Alieva Krasheninnikova, Tatiana author Calvo Padilla, María Luisa author Scott, Alan author Solheim, Brian author Xu, Dan-Xia author Delâge, André author 2007-12-10 We present an analysis of Fourier-transform arrayed waveguide gratings in the Fresnel diffraction regime. We report a distinct spatial modulation of the interference pattern referred to as the Moire-Talbot effect. The effect and its influence in a FT AWG device is explained by deriving an original analytical expression for the modulated field, and is also confirmed by numerical simulations using the angular spectrum method to solve the Fresnel diffraction integral. We illustrate the retrieval of spectral information in a waveguide Fourier-transform spectrometer in the presence of the Moire-Talbot effect. The simulated device comprises two interleaved waveguide arrays each with 180 waveguides and the interference order of 40. It is designed with a Rayleigh spectral resolution of 0.1 nm and 8 nm bandwidth at wavelength λ~1.5 µm. We also demonstrate by numerical simulations that the spectrometer crosstalk is reduced from -20 dB to -40 dB by Gaussian apodization. 1094-4087 10.1364/OE.15.016431 https://hdl.handle.net/20.500.14352/51040 http://dx.doi.org/10.1364/OE.15.016431 http://www.opticsinfobase.org/ Fresnel diffraction effects in Fourier-transform arrayed waveguide grating spectrometer