Realizing high-fidelity optical information transmission through a scattering medium is of vital importance in both science and applications, such as short-range fiber communication and optical encryption.Theoretically, an input wavefront can be reconstructed by inverting the transmission matrix of the scattering medium.However, this deterministic method for retrieving light field information encoded in the wavefront has not yet been experimentally demonstrated.Herein, we demonstrate light field information transmission through different scattering media with near-unity fidelity.Multi-dimensional optical information can be delivered through either a multimode fiber or a ground glass without relying on any averaging or approximation, where their Pearson correlation coefficients can be up to 99%.
Realizing high-fidelity optical information transmission through a scattering medium is of vital importance in both science and applications, such as short-range fiber communication and optical encryption.Theoretically, an input wavefront can be reconstructed by inverting the transmission matrix of the scattering medium.However, this deterministic method for retrieving light field information encoded in the wavefront has not yet been experimentally demonstrated.Herein, we demonstrate light field information transmission through different scattering media with near-unity fidelity.Multi-dimensional optical information can be delivered through either a multimode fiber or a ground glass without relying on any averaging or approximation, where their Pearson correlation coefficients can be up to 99%.
We report a novel optical encryption strategy that utilizes highly scattered wavefront of light field to encrypt the plaintext and exploits a scattering medium as the unique physical key. For information decryption, an imaging technique based on the speckle-correlation scattering matrix is adopted to directly extract the wavefront information from speckles, i.e., the ciphertext. The decryption relies on the transmission matrix of the scattering medium which serves as the unique key. In particular, different parts of a scattering medium have absolutely different TMs. Thus, even if attackers get the cryptosystem and repeat the measurement process, they cannot recover the key without knowing the exact part of the medium we used. The security of this scheme is further guaranteed by the advantage that data cannot be leaked without a large percentage (>60%) of the key eavesdropped. In addition, its feasibility and advantage are demonstrated experimentally.
We report a different class of ghosts, called ghost diffraction and transmission with compressed spectrum coefficients, for ghost (e.g., analog-signal) transmission in free space through scattering media using a single-pixel detector. The ghost, e.g., analog signal, is first transformed to its spectral domain, such as Hadamard domain. The generated Hadamard spectrum coefficients can be flexibly compressed in order to reduce the number of random patterns to be illuminated and transmitted in free space, and the selected Hadamard spectrum coefficients are sequentially encoded into random amplitude-only patterns as information carriers. In the experiments, high-quality Hadamard spectrum transmission using a coherent light source is realized in different scattering environments, and, subsequently, high-fidelity ghosts are further retrieved from the received Hadamard spectrum coefficients. Experimental results demonstrate that the proposed method possesses high robustness against wave diffraction, multi-layer scattering, and noise. This class of ghosts provides a different insight about quantum and classical optics for analog-signal transmission in free space, and an avenue toward many applications, e.g., quantum ghost transmission and communication, could be opened up.
Quantum communication aims to provide absolutely secure transmission of secret information. Existing methods encode symbols into single photons or coherent light with much less than one photon on average. Here we propose and demonstrate an original method that is fundamentally secure with weak coherent light even when several photons per symbol are used. Our method does not require a change of measurement basis and works with a high-dimensional alphabet in a simple practical setup. Moreover, it sends information in a deterministic way, allowing direct decoding at the receiver end. This feature makes the method suitable for both quantum key distribution (QKD) as well as quantum secure direct communication (QSDC). The key element of our method is the combination of wavefront shaping with a multimode fiber channel. Since it is based on an optical fiber, our method allows to naturally extend secure communication to larger distances.
Abstract Optical encryption is an emerging technique that uses optical systems to securely encode and decode information for data transmission. In this study, we present an integrated optical encryption platform that consists of a scattering-augmented ptychographic encryption system, a transmission-efficient compressive sampling strategy, and a high-capacity decryption algorithm based on a hybrid model-data driven approach. Our encryption system leverages random light scattering as a physical unclonable function, enabling the encoding of complex object wavefronts with high optical throughput. In contrast to traditional encoders that offer insecure pseudo-randomness, the light scattering process ensures true randomness in the reported platform. To optimize transmission efficiency, we implement a compressive sampling strategy that reduces data transmission volume by at least one order of magnitude. Moreover, we devise a decryption algorithm that merges model-driven optimization with data-driven deep learning, effectively addressing the highly underdetermined retrieval task and providing robust decryption against various measurement noise and communication interference. The efficacy of our system is corroborated by an integrated optical prototype capable of encrypting ten million of pixels within minutes. Communication experiments confirm the resilience of our decryption algorithm, which retrieves high-fidelity results even under extreme transmission conditions characterized by a 20% bit error rate. Our innovative encryption technique presents a comprehensive solution for high-capacity data transmission, fortified by scattering-augmented security.
This study falls within the emerging field of quantum optics in scattering media. By employing wavefront shaping, researchers successfully transmitted spatially entangled photon pairs through scattering media, mitigating optical disturbances by wavefront shaping. They maintained entanglement with a dimensionality of 17 after propagation, opening avenues for applications in quantum microscopy and quantum communication. Interestingly, this work also shows that in certain cases, quantum entanglement can be transmitted through a complex medium, while classical light remains scattered.
Data proliferation in the digital age necessitates robust encryption techniques to protect information privacy. Optical encryption leverages the multiple degrees of freedom inherent in light waves to encode information with parallel processing and enhanced security features. However, implementations of large-scale, high-security optical encryption have largely remained theoretical or limited to digital simulations due to hardware constraints, signal-to-noise ratio challenges, and precision fabrication of encoding elements. Here, we present an optical encryption platform utilizing scattering multiplexing ptychography, simultaneously enhancing security and throughput. Unlike optical encoders which rely on computer-generated randomness, our approach leverages the inherent complexity of light scattering as a natural unclonable function. This enables multi-dimensional encoding with superior randomness. Furthermore, the ptychographic configuration expands encryption throughput beyond hardware limitations through spatial multiplexing of different scatterer regions. We propose a hybrid decryption algorithm integrating model- and data-driven strategies, ensuring robust decryption against various sources of measurement noise and communication interference. We achieved optical encryption at a scale of ten-megapixel pixels with 1.23 µm resolution. Communication experiments validate the resilience of our decryption algorithm, yielding high-fidelity results even under extreme transmission conditions characterized by a 20% bit error rate. Our encryption platform offers a holistic solution for large-scale, high-security, and cost-effective cryptography.