Design Rules for Single-Mode and Polarization-Independent Silicon-on-Insulator Rib Waveguides Using Stress Engineering

Abstract

Abstract-There is a trend towards miniaturization of silicon photonic circuits due to superior performance and small cost. Design rules that must be imposed on the geometry of optical waveguides to make them behave as polarization-independent and singlemode devices are well known for waveguides with relatively large cross sections and for some small cross-sectional rib waveguides with vertical sidewalls and an air top cladding. The influence of the top oxide cover on waveguide birefringence was analyzed recently, but only for relatively large cross-sectional waveguides. This paper reports simulations for both single-mode and polarization-independent behavior for small cross-sectional waveguides with variable rib width, etch depth, top oxide cover thickness, and sidewall angle. The results show that the stress-induced effects must be taken into account to satisfy both requirements. Design rules to maintain birefringence-free operation and to satisfy single-mode behavior for small rib silicon-on-insulator (SOI) waveguides are presented.

Rib waveguides for mid-infrared silicon photonics

“…Field profile is strongly dependent on the waveguide geometry, and in some cases we found that the more critical higher-order mode was the quasi-TM 01 mode, while in other cases it was the quasi-TM 10 . In common with our previous work [24,25], we found that satisfying the single-mode condition (SMC) for the TM mode is again more restrictive than for the TE mode. The area below the SMC for quasi-TM mode defines the global condition for the single-mode behavior.…”

A search-and-track algorithm for controlling the number of guided modes of planar optical waveguides with arbitrary refractive index profiles

“…In spite of its similarity to previously reported results on the TM-like control of the SMC of deeply-etched small rib waveguides (Chan et al 2005), distinct differences apply. These differences include the contribution of the minor transverse field components of these rib guides to their modal cutoff as well as the stress-induced birefringence caused by the upper cladding layer Milosevic et al 2008). …”

High transmission through a 90° bend in a polarization-independent single-mode photonic crystal waveguide

“…Single-mode and polarization-independence are desirable conditions for optical waveguides [1][2][3][4][5][6]. Single-mode operation is necessary to avoid signal distortion due to different mode group velocities.…”

“…Single-mode and polarization-independent waveguides have been reported for silicon-oninsulator (SOI) rib waveguides [1,2] and with rib waveguides having sidewall angles [4]. Single-mode and polarization-independent propagation based on SOI rib waveguides and photonic wires has been investigated at the submicron scale [3].…”