Phase closure retrieval in an infrared-to-visible upconversion interferometer for high resolution astronomical imaging

Abstract

This paper demonstrates the use of a nonlinear upconversion process to observe an infrared source through a telescope array detecting the interferometric signal in the visible domain. We experimentally demonstrate the possibility to retrieve information on the phase of the object spectrum of an infrared source by using a three-arm upconversion interferometer. We focus our study on the acquisition of phase information of the complex visibility by means of the phase closure technique. In our experimental demonstration, a laboratory binary star with an adjustable photometric ratio is used as a test source. A real time comparison between a standard three-arm interferometer and our new concept using upconversion by sum-frequency generation demonstrates the preservation of phase information which is essential for image reconstruction.

Demonstration of a frequency spectral compression effect through an up-conversion interferometer

“…To experimentally retrieve the theoretical frequency compression effect reported in the previous section, we implemented an experimental setup based on the up-conversion interferometer previously developed in our laboratory [5,6,11]. In the current setup, the pump is composed of a spectral doublet to convert one input signal composed of two different frequency lines.…”

“…In the field of high resolution imaging, we have recently demonstrated the ability to analyze the coherence properties of an infrared source through an up-conversion process in a two and a three-arm interferometer [5,6]. All over these first experiments, we were limited by the intrinsic spectral acceptance of the PPLN waveguides: if a large spectral bandwidth source at infrared wavelengths is converted through a SFG process with a single line pump, the PPLN spectral acceptance limits the nonlinear effect to a very narrow spectral bandwidth of the source.…”

Proposal for the Implementation of the ALOHA Up-Conversion Interferometer on the CHARA Telescope Array

“…Using a fixed telescope configuration and changing the power ratio between the two components of a laboratory binary star, it has been possible to scan a large domain of phase closure values. Ceus et al (2011) reports on the very good accuracy of the SFG interferometer measurements using the MAFL instrument as a reference. Nevertheless, these last measurements were always performed at high flux level.…”

“…The implementation of the ALOHA instrument on the CHARA array uses the Fiber Linked Unit of Optical Recombination (FLUOR) instrument (Coudé du Foresto et al, 2003). This instrument is a two-arm fiber-based beam combiner.…”

Simple alternative model of the dual nature of light and its Gedanken experiment

“…• Finally, it can survive to frequency up-conversion from infrared to visible spectral domains, operated by two or more separated nonlinear optical frequency converters [12].…”