A compact slot waveguide directional coupler-based silicon-on-insulator polarization splitter

Abstract

Abstract-A compact directional coupler-based polarization splitter is designed and realized using silicon-on-insulator (SOI) waveguides. Even though silicon does not have any material birefringence, the high index contrast obtained in the SOI platform and reduced waveguide dimensions makes it possible to induce significant birefringence. Polarization splitting is achieved by making use of this geometry-induced birefringence. In this work, we demonstrate polarization splitting in devices as short as 120 m. Even smaller devices can be made using submicron-thick Si waveguides.

Ultracompact polarization splitter–rotator based on an asymmetric directional coupler

“…After rotating and passing through photonic structures in one arm, while in the other arm first passing through the same photonic structures then rotating, the two arms will be combined at the output of the chip, just as described in [2]. Therefore, the key elements of the polarization diversity system are the polarization splitter [5][6][7][8][9][10] and the polarization rotator [11][12][13][14][15]. Generally, the polarization splitter and the polarization rotator are separate devices.…”

“…For the vertical SW, the quasi-TE mode is confined strongly in the slot region, which could be used to enhance nonlinear effects for optical modulation and detection [20,21]. Meanwhile, various passive devices based on the SW have been reported [6][7][8][9]11,12]. Because the effective index of the SW is lower than for the corresponding CW, which means weak confinement for the optical field and leads to a shorter coupling length between the two adjacent waveguides, the polarization splitter-rotator (PSR) would be more compact than the complete CW device.…”