Laser-written scalable sapphire integrated photonics platform

TL;DR

This paper presents a scalable method for integrating single-mode photonic devices on sapphire substrates using femtosecond laser direct writing, enabling advanced applications in communications, imaging, and sensing.

Contribution

It introduces a multi-layer depressed cladding waveguide platform on sapphire with low propagation losses and complex integrated photonic structures fabricated via adaptive optics-assisted femtosecond laser writing.

Findings

Propagation losses of ~0.6 dB/cm at 780 nm and ~0.7 dB/cm at 1550 nm

Fabrication of various integrated structures including splitters and interferometers

Successful demonstration of scalable, single-mode sapphire photonics platform

Abstract

In this paper, we demonstrate the integration of photonic devices on sapphire substrates using multi-layer depressed cladding waveguides at both 780 nm and 1550 nm. The devices are up to 10-cm long and written at depths down to 400 um. The propagation losses for single-mode guiding are ~ 0.6 dB/cm at 780 nm and ~ 0.7 dB/cm at 1550 nm. A number of structures have been fabricated with simultaneous single-mode and polarization independent operation: evanescently coupled waveguide arrays, Y-branch splitters, Mach-Zehnder interferometers, and a 2x2 directional-coupler. All the devices were fabricated using adaptive optics-assisted femtosecond laser direct writing with a customized laser writing algorithm. This work enables the integration of single-mode sapphire photonics devices in a scalable manner, enabling many applications in communications, imaging, computing, and sensing.