Highly efficient coupling from an optical fiber to a nanoscale silicon optomechanical cavity

TL;DR

This paper presents a highly efficient, broadband fiber-to-chip coupling method using an adiabatic coupler, achieving 85% efficiency in silicon photonic cavities, enhancing integration of fiber optics with nanoscale photonic devices.

Contribution

The authors introduce a compact, lithographically controlled adiabatic coupler for efficient fiber-to-chip optical coupling in silicon photonics.

Findings

Achieved 85% fiber-to-cavity coupling efficiency.

Demonstrated broadband and alignment-insensitive coupling.

Compatible with various photonic chips with higher refractive index.

Abstract

We demonstrate highly efficient coupling of light from an optical fiber to a silicon photonic crystal optomechanical cavity. The fiber-to-cavity coupling utilizes a compact (L ~ 25 um) intermediate adiabatic coupler. The optical coupling is lithographically controlled, broadband, relatively insensitive to fiber misalignment, and allows for light to be transferred from an optical fiber to, in principle, any photonic chip with refractive index greater than that of the optical fiber. Here we demonstrate single-sided cavity coupling with a total fiber-to-cavity optical power coupling efficiency of 85%.