The effects of roughness induced backscattering in optical waveguides and circuit realized on a silicon-on-insulator platform are investigated. A systematic experimental investigation on low-loss silicon nanowires, with a sidewall roughness rms around 1-2 nm, is presented, showing that a few hundreds of micrometers long waveguide exhibits a backscattering level that can hinder its exploitation in many applications. The effect is typically stronger for TE polarization and is significantly enhanced inside optical cavities, such as microring resonators, where backscattering is coherently enhanced according to the square of the finesse of the resonator and can modify dramatically the spectral response of the resonators, even at moderate quality factors. We found general relationships relating backscattering to the geometric and optical parameters of the waveguides, to polarization rotation effects, and to coupling with higher-order modes. On the basis of these results, design rules to mitigate backscattering effects are proposed. The main statistical properties of roughness induced backscattering were also experimentally derived, these results enabling an accurate modeling of realistic waveguides and the evaluation of the backscattering impact in integrated devices and circuits.

Backscattering in silicon photonic waveguides and circuits

MORICHETTI, FRANCESCO;CANCIAMILLA, ANTONIO;FERRARI, CARLO;MARTINELLI, MARIO;MELLONI, ANDREA IVANO
2011

Abstract

The effects of roughness induced backscattering in optical waveguides and circuit realized on a silicon-on-insulator platform are investigated. A systematic experimental investigation on low-loss silicon nanowires, with a sidewall roughness rms around 1-2 nm, is presented, showing that a few hundreds of micrometers long waveguide exhibits a backscattering level that can hinder its exploitation in many applications. The effect is typically stronger for TE polarization and is significantly enhanced inside optical cavities, such as microring resonators, where backscattering is coherently enhanced according to the square of the finesse of the resonator and can modify dramatically the spectral response of the resonators, even at moderate quality factors. We found general relationships relating backscattering to the geometric and optical parameters of the waveguides, to polarization rotation effects, and to coupling with higher-order modes. On the basis of these results, design rules to mitigate backscattering effects are proposed. The main statistical properties of roughness induced backscattering were also experimentally derived, these results enabling an accurate modeling of realistic waveguides and the evaluation of the backscattering impact in integrated devices and circuits.
Proc. of SPIE vol. 7943
9780819484802
TLC
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11311/634956
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 3
  • ???jsp.display-item.citation.isi??? 2
social impact