Wafer-Scale Fabrication of InGaP-on-Insulator for Nonlinear and Quantum Photonic Applications

TL;DR

This paper presents a scalable wafer-scale fabrication process for InGaP-on-insulator, enabling high-quality nonlinear photonic components suitable for quantum and classical optical applications.

Contribution

It introduces a novel wafer-scale InGaP-on-insulator platform with high-Q resonators and detailed fabrication techniques for nonlinear photonics.

Findings

High resonator quality factors up to 440,000 achieved.

Successful fabrication of complex photonic components on 100-mm wafers.

Potential for quantum light sources due to high nonlinearity and low loss.

Abstract

The development of manufacturable and scalable integrated nonlinear photonic materials is driving key technologies in diverse areas such as high-speed communications, signal processing, sensing, and quantum information. Here, we demonstrate a novel nonlinear platform -- InGaP-on-insulator -- optimized for visible-to-telecommunication wavelength $\chi^{\left(2\right)}$ nonlinear optical processes. In this work, we detail our 100-mm wafer-scale InGaP-on-insulator fabrication process realized via wafer bonding, optical lithography, and dry-etching techniques. The resulting wafers yield 1000s of components in each fabrication cycle, with initial designs that include chip-to-fiber couplers, 12.5-cm-long nested spiral waveguides, and arrays of microring resonators with free-spectral ranges spanning 400-900 GHz. We demonstrate intrinsic resonator quality factors as high as 324,000 (440,000) for single-resonance (split-resonance) modes near 1550 nm corresponding to 1.56 dB cm$^{-1}$ (1.22 dB cm$^{-1}$) propagation loss. We analyze the loss versus waveguide width and resonator radius to establish the operating regime for optimal 775-to-1550 nm phase matching. By combining the high $\chi^{\left(2\right)}$ and $\chi^{\left(3\right)}$ optical nonlinearity of InGaP with wafer-scale fabrication and low propagation loss, these results open promising possibilities for entangled-photon, multi-photon, and squeezed light generation.