title: Silicon band-rejection and band-pass filter based on asymmetric Bragg sidewall gratings in a multimode waveguide.
abstract: A silicon photonic wire filter based on an asymmetric sidewall Bragg grating in a multimode silicon-on-insulator strip waveguide is demonstrated. The operating principle is based on the contra-directional coupling between the transverse electric fundamental (TE0) and first-order (TE1) modes, which is enabled by the asymmetric spatially periodic refractive-index perturbations. An asymmetric Y-junction is cascaded at the input port of the filter so as to drop the Bragg reflection. Compared with conventional Bragg grating-based filters, this device eliminates the back reflection at the input port and the 6 dB inherent insertion loss at the drop port; moreover, a narrow 3 dB bandwidth can be obtained with a large critical dimension as a result of the weak coupling strength between the TE0 and TE1 modes inside the multimode waveguide. Experimental results show that a bandwidth of ∼2.8  nm is achieved by a large corrugation width of 150 nm. The insertion loss at the drop port is -2.1  dB, and the extinction ratio is -33  dB at the through port.
authors.forename: Huiye
authors.initials: H
authors.lastname: Qiu
authors.forename: Jianfei
authors.initials: J
authors.lastname: Jiang
authors.forename: Ping
authors.initials: P
authors.lastname: Yu
authors.forename: Tingge
authors.initials: T
authors.lastname: Dai
authors.forename: Jianyi
authors.initials: J
authors.lastname: Yang
authors.forename: Hui
authors.initials: H
authors.lastname: Yu
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Jiang