Critical optical coupling between a GaAs disk and a nanowaveguide suspended on the chip

TL;DR

This paper demonstrates critical optical coupling between a GaAs disk and a suspended nanowaveguide on a chip, achieving efficient evanescent coupling in an integrated photonic system.

Contribution

It introduces a novel integrated GaAs disk/waveguide system with tunable critical coupling achieved through gap and taper width adjustments.

Findings

Achieved critical coupling in a GaAs disk/waveguide system.

Experimental results match coupled mode theory predictions.

Demonstrated control over coupling regime via geometric tuning.

Abstract

We report on an integrated GaAs disk/waveguide system. A millimeter-long waveguide is suspended and tapered on the chip over a length of 25 {\mu}m to evanescently couple to high Q optical whispering gallery modes of a GaAs disk. The critical coupling regime is obtained both by varying the disk/guide gap distance and the width of the suspended nanoscale taper. The experimental results are in good agreement with predictions from the coupled mode theory.