title: Symmetrical polarization splitter/rotator design and application in a polarization insensitive WDM receiver.
abstract: In integrated photonics, the design goal of a polarization splitter/rotator (PSR) has been separating the TE0 and TM0 modes in a waveguide. This is a natural choice. But in theory, a PSR only needs to project the incoming State Of Polarization (SOP) orthogonally to its output ports, using any orthogonal mode basis set in the fiber. In this article, we introduce a novel PSR design that alternatively takes the linear combination of TE0 and TM0 (TE0 +/- TM0) as orthogonal bases. By contrast, existing approaches exclusively use TE0 and TM0 as their basis set. The design is based on two symmetric and robust structures: a bi-layer taper and a Y-junction, and involves no bends. To prove the concept, we incorporated it into a four-channel polarization insensitive wavelength division multiplexing (PI-WDM) receiver fabricated in a standard CMOS Si photonics process. 40 Gb/s data rate and 0.7 +/- 0.2 dB polarization dependent loss (PDL) is demonstrated on each channel. Lastly, we propose an improved PSR design with 12 μm device length, < 0.1 dB PDL, < 0.4 dB insertion loss and < 0.05 dB wavelength dependence across C-band for both polarizations. Overall, our PSR design concept is simple, easy to realize and presents a new perspective for future PSR designs.
authors.forename: Yangjin
authors.initials: Y
authors.lastname: Ma
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Hang
authors.initials: H
authors.lastname: Guan
authors.forename: Alexander
authors.initials: A
authors.lastname: Gazman
authors.forename: Qi
authors.initials: Q
authors.lastname: Li
authors.forename: Ran
authors.initials: R
authors.lastname: Ding
authors.forename: Yunchu
authors.initials: Y
authors.lastname: Li
authors.forename: Keren
authors.initials: K
authors.lastname: Bergman
authors.forename: Tom
authors.initials: T
authors.lastname: Baehr-Jones
authors.forename: Michael
authors.initials: M
authors.lastname: Hochberg