Group index and group velocity dispersion in silicon-on-insulator photonic wires

TLDR

The study measures the group index and group‑velocity dispersion of 525 × 226 nm silicon‑on‑insulator strip waveguides across the telecom band using an integrated Mach‑Zehnder interferometer. The GVD is dominated by strong optical confinement rather than material dispersion, and the measured group index and GVD serve as benchmarks for comparing four theoretical models. Measured GVD is 4400 ps/(nm·km) at 1550 nm, nearly three orders of magnitude higher than standard fibers, yet dispersion‑induced impairments remain negligible for data rates up to 100 Gb/s over waveguide lengths up to about 1 m.

Abstract

We determine group index and group velocity dispersion (GVD) of SOI single-mode strip waveguides (photonic wires) with 525x226nm cross-section over the entire telecommunication bandwidth by employing an integrated Mach-Zehnder interferometer. The measured GVD yields 4400 ps/(nm*km) at 1550 nm and exceeds that of standard single-mode fibers by almost three orders of magnitude. In the photonic wires the GVD is mainly determined by strong light confinement rather than by material dispersion. Our results indicate that despite this high GVD, dispersion-induced signal impairment is negligible in photonic circuits for data rates up to 100-Gb/s and total waveguide lengths as long as about 1 meter. The measured group index and GVD are used as benchmarks to compare model calculations originating from four different theoretical methods.