Component-wise testing of laser-written integrated coupled-mode beam splitters.

Jun Guan,Martin J Booth,Xiang Liu,Adrian J Menssen,Jingyu Wang

doi:10.1364/ol.44.003174

Abstract

Photonic integrated circuits (PICs) are important enabling technologies for the developments of areas such as quantum information processing (QIP). Coupled-mode integrated beam splitters (IBS) are widely used in many PICs, so direct and accurate testing of individual IBSs inside a PIC is increasingly desirable, as the development of PICs for QIP is scaled up. Here we demonstrate a solution for component-wise testing of coupled-mode IBSs without limitations on component location and PIC architectures. The method is based on the imaging of an individual IBS with a custom-built multifunctional adaptive optical microscope, combined with the calculation of its beam-splitting ratio through numerical modelling.

Highlights

Accurate testing of the beam-splitting ratio of individual integrated beam splitters (IBS) inside a Photonic integrated circuits (PICs) is an important part of the full characterization of a quantum PIC [15,19,20,21,22]
Methods for relaxing the fabrication tolerances of directional coupler (DC) in a PIC, such as the one proposed by Miller [21], in practice, will lose their validity for larger-scale quantum PICs, because the involved additional circuit complexity will incur extra manufacture cost, and critically increase the overall circuit loss, bearing in mind that low loss is critical in many quantum applications [15,18,19]
We demonstrate a solution for a component-wise test of a coupled-mode IBS by first imaging the IBS under test with the third-harmonic generation (THG) module of a custom-built three-dimensional (3D) adaptive multifunctional microscope and measuring the waveguide projected refractive index change with its quantitative phase microscopy (QPM) module, ascertaining its beam-splitting ratio with a numerical simulation model

Summary

Introduction

We demonstrate a solution for a component-wise test of a coupled-mode IBS by first imaging the IBS under test with the third-harmonic generation (THG) module of a custom-built three-dimensional (3D) adaptive multifunctional microscope and measuring the waveguide projected refractive index change with its quantitative phase microscopy (QPM) module, ascertaining its beam-splitting ratio with a numerical simulation model.

Results

Conclusion