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Strong pump rejection filter for polarization-diverse silicon platforms

2021; Optica Publishing Group; Volume: 47; Issue: 2 Linguagem: Inglês

10.1364/ol.444258

1539-4794

Jérôme Michon, Xavier Le Roux, Alexandre Huot de Saint-Albin, Dorian Oser, Sébastien Tanzilli, Laurent Labonté, Éric Cassan, Laurent Vivien, Carlos Alonso‐Ramos,

Optical Network Technologies

Integrated wavelength filters with high optical rejection are key components in several silicon photonics circuits, including quantum photon-pair sources and spectrometers. Non-coherent cascading of modal-engineered Bragg filters allows for remarkable optical rejections in structures that only support transverse-electric (TE) polarized modes such as uncladded 220-nm-thick silicon. However, the restriction to TE-only platforms limits the versatility of the non-coherent cascading approach. Here, we propose and experimentally demonstrate a new, to the best of our knowledge, approach for high-rejection filters in polarization-diverse platforms by combining non-coherent cascading of modal-engineered Bragg filters and anisotropy-engineered metamaterial bends. Bragg filters provide a high rejection of the TE mode, while the metamaterial bends remove any residual power propagating in the transverse-magnetic (TM) mode, without any penalty in terms of insertion loss or device footprint. Based on this strategy, we demonstrate optical rejection exceeding 60 dB in 300-nm-thick, cladded silicon waveguides.