On-chip spectro-detection for fully integrated coherent beam combiners

TL;DR

This paper introduces on-chip spectro-detection using SWIFTS technology for integrated coherent beam combiners, enabling full spectral and spatial sampling with potential for photon-counting in astrophysical interferometry.

Contribution

It proposes a novel on-chip detection principle (SWIFTS) that allows direct spectral sampling and photon-counting, extending capabilities of integrated interferometric instruments.

Findings

Demonstrated feasibility of SWIFTS-based on-chip spectro-detection

Implemented three practical beam combination configurations

Achieved pair-wise baseline coding for data processing

Abstract

This paper presents how photonics associated with new arising detection technologies is able to provide fully integrated instrument for coherent beam combination applied to astrophysical interferometry. The feasibility and operation of on-chip coherent beam combiners has been already demonstrated using various interferometric combination schemes. More recently we proposed a new detection principle aimed at directly sampling and extracting the spectral information of an input signal together with its flux level measurement. The so-called SWIFTS demonstrated concept that stands for Stationary-Wave Integrated Fourier Transform Spectrometer, provides full spectral and spatial information recorded simultaneously thanks to a motionless detecting device. Due to some newly available detection principles considered for the implementation of the SWIFTS concept, some technologies can even provide photo-counting operation that brought a significant extension of the interferometry domain of investigation in astrophysics . The proposed concept is applicable to most of the interferometric instrumental modes including fringe tracking, fast and sensitive detection, Fourier spectral reconstruction and also to manage a large number of incoming beams. The paper presents three practical implementations, two dealing with pair-wise integrated optics beam combinations and the third one with an all-in-one 8 beam combination. In all cases the principles turned into a pair wise baseline coding after proper data processing.