Fabrication of low-loss III-V Bragg-reflection waveguides for parametric down-conversion

TL;DR

This paper reports the improved fabrication of low-loss III-V Bragg-reflection waveguides, significantly enhancing photon pair production rates for quantum communication applications.

Contribution

The authors developed a fabrication process using advanced lithography and etching techniques to reduce sidewall roughness and optical losses in Bragg-reflection waveguides.

Findings

Achieved a low optical loss coefficient of 0.08 mm^(-1).

Realized a 15-fold increase in photon pair production rate.

Demonstrated improved waveguide fabrication for quantum photonics.

Abstract

Entangled photon pairs are an important resource for quantum cryptography schemes that go beyond point-to-point communication. Semiconductor Bragg-reflection waveguides are a promising photon-pair source due to mature fabrication, integrability, large transparency window in the telecom wavelength range, integration capabilities for electro-optical devices as well as a high second-order nonlinear coefficient. To increase performance we improved the fabrication of Bragg-reflection waveguides by employing fixed-beam-moving-stage optical lithography, low pressure and low chlorine concentration etching, and resist reflow. The reduction in sidewall roughness yields a low optical loss coefficient for telecom wavelength light of alpha_reflow = 0.08(6)mm^(-1). Owing to the decreased losses, we achieved a photon pair production rate of 8800(300)(mW*s*mm)^(-1) which is 15-fold higher than in previous samples.