RESEARCH NEWS
Programmable photonic chip restores chaotic signals degraded by turbulence, enabling robust, secure free-space optical links
The increasing demand for secure, high-capacity, and low-latency wireless communication systems has brought renewed attention to freespace optical( FSO) links, especially for line-of-sight applications. However, ensuring secure and reliable data transmission over FSO channels remains a major challenge due to their susceptibility to atmospheric turbulence, which induces beam scintillation, wandering, and random fading. In this context, chaos-based optical communication has emerged as a promising physical-layer security technique, leveraging the broadband, aperiodic, and highly sensitive nature of chaotic signals to encode information with high entropy and low predictability.
In this work, researchers present the first direct experimental evidence of the degradation of chaotic optical signals caused by atmospheric turbulence, and demonstrate a silicon photonic solution capable of fully recovering their complexity in real time. The turbulent environment is emulated using a spatial light modulator programmed with phase screens derived from the Modified Von Kármán Spectrum. To restore the chaotic signal, they utilize a self-adaptive multi-aperture receiver comprising a two-dimensional array of grating couplers and a programmable optical processor( POP) based on a mesh of Mach – Zehnder interferometers. The POP autonomously compensates for phase distortions by means of real-time local feedback loops, enabling coherent recombination of spatially distorted wavefronts.
REFERENCE Zaminga, S., Martinez, A., Huang, H. et al. Optical chaotic signal recovery in turbulent environments using a programmable optical processor. Light Sci. Appl. 14, 131( 2025). https:// doi. org / 10.1038 / s41377-025-01784-3
SINGLE PHOTON SOURCE IN THE MID-INFRARED( MIR) RANGE
Single photons are essential for quantum metrology and precision spectroscopy, where they significantly enhance measurement accuracy. While most existing single-photon sources( SPEs) operate in the visible and near-infrared ranges, their efficiency declines significantly in the MIR and terahertz domains. Advancing MIR single-photon sources could enable groundbreaking applications, such as non-invasive biological imaging, pollutant detection in biological fluids, and in-depth studies of molecular vibrations. In the study, researchers at the Max Planck Institute for the Structure and Dynamics of Matter( MPSD) in collaboration with DTU Electro, the University of Sheffield and the University of Copenhage developed a technique that leverages the coupling between visible-frequency single-photon sources and phonons— vibrational modes of a material’ s crystal lattice— to generate single MIR photons. The process enhances specific optical transitions, first preparing a phonon mode in a quantum state before converting it into a single MIR photon via a specially designed antenna. This method not only enables on-demand single-photon generation but is also adaptable to a wide range of quantum emitters, including two-dimensional materials, nanocrystals, and molecular systems. The results pave the way for further exploration of cavityengineered solid-state materials and the expansion of quantum electrodynamics( QED) in the MIR regime.
REFERENCE J. Iles-Smith, M. K. Svendsen, A. Rubio, M. Wubs and N. Stenger, On-demand heralded MIR single-photon source using a cascaded quantum system. Science Advances 11, eadr9239( 2025). https:// doi. org / 10.1126 / sciadv. adr9239
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