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Proceedings Paper

Optical diffraction into thick slab waveguides: a finite-beam RCWA approach to solve extremely asymmetrical scattering-EAS in slanted holographic gratings
Author(s): Silvia M. Pietralunga; Alessandro Geroldi; Mirko Serafini
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Paper Abstract

We have implemented a Finite-Beam Rigorous Coupled-Wave Approach (FB-RCWA) to solve for guided-optics propagation in the presence of holographic slanted Bragg gratings, embedded in the core of slab waveguides and operated in Extreme Asymmetrical Scattering (EAS) configuration. In EAS a resonance condition can be established, as proceeding from the design parameters. Diffraction efficiency can be evaluated as the ratio of the flux of diffracted power P1, on a suitably defined cross-section along the propagation of diffracted beam, and input power P0. By FBRCWA, no limitation in the depth of grating modulation is assumed. The first-order diffracted field in resonant Bragg condition propagates along the waveguide. EAS in thick waveguides operating in highly multimodal regime can be investigated, as well as macroscopic volumes and widely extended illuminated regions up to a few millimeters. In thick slabs, η > 90% is demonstrated, for input illuminated apertures of length L ≥ Lc, where Lc is the optimum coupling length. The effects of detuning from Bragg condition, both in distribution and amplitude of the diffracted field, are quantified. Diffraction efficiency, i.e. optical coupling, bandwidth is evaluated.

Paper Details

Date Published: 9 May 2012
PDF: 9 pages
Proc. SPIE 8428, Micro-Optics 2012, 84280E (9 May 2012); doi: 10.1117/12.918558
Show Author Affiliations
Silvia M. Pietralunga, Istituto di Fotonica e Nanotecnologie, CNR, Politecnico di Milano (Italy)
Alessandro Geroldi, Politecnico di Milano (Italy)
Mirko Serafini, Politecnico di Milano (Italy)

Published in SPIE Proceedings Vol. 8428:
Micro-Optics 2012
Hugo Thienpont; Jürgen Mohr; Hans Zappe; Hirochika Nakajima, Editor(s)

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