Spatially resolving amplitude and phase of light with a reconfigurable photonic integrated circuit

TL;DR

This paper demonstrates a reconfigurable photonic integrated circuit capable of spatially resolving the amplitude and phase of free-space light beams, with a versatile calibration method effective across various wavelengths.

Contribution

It introduces a novel method for calibrating and operating reconfigurable PICs to measure light amplitude, phase, and polarization in a wide parameter range.

Findings

Successful experimental implementation of the sampling technique

Effective calibration method applicable off the design wavelength

Potential applications in advanced optical sensing and measurement

Abstract

Photonic integrated circuits (PICs) play a pivotal role in many applications. Particularly powerful are circuits based on meshes of reconfigurable Mach-Zehnder interferometers as they enable active processing of light. Various possibilities exist to get light into such circuits. Sampling an electromagnetic field distribution with a carefully designed free-space interface is one of them. Here, a reconfigurable PIC is used to optically sample and process free-space beams so as to implement a spatially resolving detector of amplitudes and phases. In order to perform measurements of this kind we develop and experimentally implement a versatile method for the calibration and operation of such integrated photonics based detectors. Our technique works in a wide parameter range, even when running the chip off the design wavelength. Amplitude, phase and polarization sensitive measurements are of enormous importance in modern science and technology, providing a vast range of applications for such detectors.