Highly Efficient Mode Converter for Coupling Light into Wide Slot Photonic Crystal Waveguide

TL;DR

This paper presents a highly efficient, low-loss adiabatic mode converter for silicon slot waveguides with large slots, significantly improving coupling efficiency into photonic crystal waveguides over a broad wavelength range.

Contribution

The authors design and experimentally demonstrate a novel adiabatic mode converter optimized for large-slot silicon waveguides, achieving lower insertion loss and higher coupling efficiency than conventional methods.

Findings

Insertion loss as low as 0.08dB

0.1dB lower loss than V-shape converter

Up to 3.5dB improved coupling efficiency

Abstract

We design, fabricate and experimentally demonstrate a highly efficient adiabatic mode converter for coupling light into a silicon slot waveguide with a slot width as large as 320nm. This strip-to-slot mode converter is optimized to provide a measured insertion loss as low as 0.08dB. Our mode converter provides 0.1dB lower loss compared to a conventional V-shape mode converter. This mode converter is used to couple light into and out of a 320nm slot photonic crystal waveguide, and it is experimentally shown to improve the coupling efficiency up to 3.5dB compared to the V-shape mode converter, over the slow-light wavelength region.