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Bunching of Broadband Multimode Thermal Light Enabled by Temporal Imaging

Filip Sośnicki, Michał Mikołajczyk, Sanjay Kapoor, Jerzy Szuniewicz, D. B. Horoshko, Mikhail I. Kolobov, Michał Karpiński

Published Jan 1, 2025• 0 citations
Publisher

Abstract

We demonstrate electro-optic temporal magnification of the time-resolved second-order coherence function, allowing us to measure maximal bunching for multimode thermal light. This technique paves the way for new advancements in intensity correlation measurements.
DOI
10.1364/cleo_fs.2025.ff140_2

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A major advance in understanding the behavior of light was to describe the coherence of a light source by using correlation functions that define the spatio-temporal relationship between pairs and larger groups of photons. Correlations are also a fundamental property of matter. We performed simultaneous measurement of the second- and third-order correlation functions for atoms. Atom bunching in the arrival time for pairs and triplets of thermal atoms just above the Bose-Einstein condensation (BEC) temperature was observed. At lower temperatures, we demonstrated conclusively the long-range coherence of the BEC for correlation functions to third order, which supports the prediction that like coherent light, a BEC possesses long-range coherence to all orders.
Working in experimental quantum optics with focus on instrumentation for temporal intensity interferometry. Have successfully measured and resolved the temporal photon bunching effect from Sunlight in Singapore despite the tropical, humid, and urban environment. Our lab measurements have successfully identified the presence of coherent laser light even when embedded in a blackbody radiation background. Measurements also differentiated coherent laser light from thermal light that are both narrowband emission lines which could otherwise be mis-identified.
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Thermal light sources exhibiting photon bunching have been suggested for sensing applications that exploit timing correlations of stationary light, including range finding, clock synchronization, and non-line-of-sight imaging. However, these proposals have remained unrealized in practice because available sources of photon bunching either possess coherence times too short to be timing resolved by photodetectors, or produce brightness levels too low to tolerate realistic return losses. In this work, we demonstrate a low-loss method for generating photon bunching with a conversion efficiency nearly 9 orders of magnitude higher than that achieved by many other bunching processes.