Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1536315 | Optics Communications | 2012 | 4 Pages |
The SOI based waveguide devices are found to be highly polarization sensitive. Unwanted polarization excitations can be attenuated by integrating a TE- or TM-pass polarizer. A large attenuation of TM-polarized light has been observed when a thin film of metal is coated on the top of silicon rib waveguide, while TE-polarized light remains almost unaffected. The attenuation of TM-polarized light is attributed to the plasmonic absorption of the evanescent field in the metal cladding. Typically, with an Al cladding of thickness ∼ 100 nm and a length of 1 mm on top of a single-mode (λ ∼ 1550 nm) SOI rib waveguide structure, TE vs TM extinction ratio of ∼ 15 dB has been obtained. Integrating such waveguide polarizers in a directional coupler and MZI based DWDM channel interleaver, we have also achieved an improvement in polarization extinction by ∼ 15 dB.