Optical pump-rejection filter based on silicon sub-wavelength engineered photonic structures

Diego Pérez-Galacho (1) , Carlos Alonso-Ramos (1) , Florent Mazeas (2) , Xavier Le Roux (1) , Dorian Oser (1) , Weiwei Zhang (1) , Delphine Marris-Morini (1) , Laurent Labonté (2) , Sébastien Tanzilli (2) , Eric Cassan (1) , Laurent Vivien (1)

1 C2N - Centre de Nanosciences et de Nanotechnologies [Orsay]
2 INPHYNI - Institut de Physique de Nice

The high index contrast of the silicon-on-insulator (SOI) platform allows the realization of ultra-compact photonic circuits. However, this high contrast hinders the implementation of narrow-band Bragg filters. These typically require corrugations widths of a few nanometers or double-etch ge-ometries, hampering device fabrication. Here we report, for the first time, on the realization of SOI Bragg filters based on sub-wavelength index engineering in a differential corrugation width configuration. The proposed double periodicity structure allows narrow-band rejection with a single etch step and relaxed width constraints. Based on this concept, we experimentally demonstrate a single-etch, 220 nm thick, Si Bragg filter featuring a corrugation width of 150 nm, a rejection bandwidth of 1.1 nm and an extinction ratio exceeding 40 dB. This represents a tenfold width increase compared to conventional single-periodicity, single-etch counterparts with similar bandwidths.

Domaines: Optique [physics.optics]

Diego Pérez-Galacho, Carlos Alonso-Ramos, Florent Mazeas, Xavier Le Roux, Dorian Oser, et al.. Optical pump-rejection filter based on silicon sub-wavelength engineered photonic structures. Optics Letters, 2017, 42 (8), pp.1468-1471. ⟨10.1364/OL.42.001468⟩. ⟨hal-01527014v2⟩