Interferometric imaging using Si3N4 photonic integrated circuits for a SPIDER imager.

Tiehui Su,Jaeyi Chun,Katherine E Badham,Shaoqi Feng,Richard L Kendrick,Alan Duncan,Guy Chriqui,Chad Ogden,S J B Yoo,Guangyao Liu,Weicheng Lai,Samuel T Thurman,Danielle Wuchenich

doi:10.1364/oe.26.012801

Abstract

This paper reports design, fabrication, and experimental demonstration of a silicon nitride photonic integrated circuit (PIC). The PIC is capable of conducting one-dimensional interferometric imaging with twelve baselines near λ = 1100-1600 nm. The PIC consists of twelve waveguide pairs, each leading to a multi-mode interferometer (MMI) that forms broadband interference fringes or each corresponding pair of the waveguides. Then an 18 channel arrayed waveguide grating (AWG) separates the combined signal into 18 signals of different wavelengths. A total of 103 sets of fringes are collected by the detector array at the output of the PIC. We keep the optical path difference (OPD) of each interferometer baseline to within 1 µm to maximize the visibility of the interference measurement. We also constructed a testbed to utilize the PIC for two-dimension complex visibility measurement with various targets. The experiment shows reconstructed images in good agreement with theoretical predictions.

Highlights

Interferometry has become an indispensable tool for modern astronomy
The telescope diameter D limits the angular resolution of the telescope to Ф ≈λ/D because of diffraction
Summary We discussed the concept of a Segmented Planar Imaging Detector for Electrooptical Reconnaissance (SPIDER) imager that has the potential to reduce SWaP compared to conventional telescopes

Summary

Introduction

Interferometry has become an indispensable tool for modern astronomy. It uses superimposed electromagnetic waves to extract information about the wave source [1, 2]. Optical interferometry brings the light of many telescopes together to create high angular resolution images. Optical interferometer arrays are the instrument of choice for high-resolution imaging. The conceptual SPIDER telescope uses multiple baselines to sample the target visibility function in the spatial frequency domain, and digitally reconstructs the object image.

Results

Conclusion