High-fidelity image reconstruction from dynamic nonlinear speckles mediated by chlorophyll solution using deep learning

Visible-light excitable thermally activated delayed fluorescence from hydrogen-bonded D-A aromatic N-heterocycle/polymer material and the application for anti-counterfeiting

Protonation induced symmetry-breaking and fluorescence switching in C3-symmetric self-assemblies with application in optical information encryption.

On July 01, 2024, a team of experts led by ZHANG Ting, WANG Zhijun, LI Panlai from the School of Hebei Key Laboratory of Optic-electronic Information and Materials published an article in the 发光学报, introducing their research progress in the field of self-recoverable mechanoluminescent phosphors. The team developed a novel phosphor Ca5Ga6O14:Eu3+, which exhibits red mechanoluminescence with good repeatability and can be tuned to green by co-doping with Tb3+. This discovery paves the way for applications in optical information encryption, offering a new direction for secure communication.

Mid-infrared pulsed lasers operating around the 3 μm wavelength regime are important for a wide range of applications including sensing, spectroscopy, imaging, etc. Despite the recent advances in technology, the lack of a nonlinear optical modulator operating in the mid-infrared regime remains a significant challenge. Here, we report the third-order nonlinear optical response of gold nanorods (GNRs) ranging from 800 nm to the mid-infrared regime (2810 nm) enabled by their size and overlapping behavior-dependent longitudinal surface plasmon resonance. In addition, we demonstrate a wavelength-tunable Er3+-doped fluoride fiber laser modulated by GNRs, which can deliver pulsed laser output, with the pulse duration down to 533 ns, tunable wavelength ranging from 2760.2 to 2810.0 nm, and spectral 3 dB bandwidth of about 1 nm. The experimental results not only validate the GNRs’ robust mid-infrared nonlinear optical response, but also manifest their application potential in high-performance broadband optoelectronic devices.

We report the spatial self-phase modulation (SSPM) effect for solution dispersions of black phosphorus (BP). The experimental results suggest that this concentration-dependent coherent light diffraction is due to the ultrafast and large third-order optical nonlinearity of BP. The third-order nonlinear susceptibility of BP has been simply obtained about 10−19 m2/V2 by analyzing the experimental results. The fast relaxation time during dynamic relaxation is obtained as 0.13 ps. Our experimental results imply novel potential application of BP in ultrafast nonlinear phase modulation devices based on their nonlinear optical response.

Application of a Derivative-Free Method with Projection Skill to Solve an Optimization Problem

Application of a Derivative-Free Method with Projection Skill to Solve an Optimization Problem

We report the first observation of non-Markovian stochastic resonance (SR), and we discover that memory effects in the nonlinearity extremely enlarge the SR bandwidth. Our experimental system is an oil-filled microcavity which, driven by a continuous wave laser, has memory in its nonlinear optical response. Modulating the cavity length while adding noise to the driving laser, we observe a peak in the transmitted signal-to-noise ratio as a function of the noise variance. Through simulations, we reproduce our observations and extrapolate that the SR bandwidth could be ∼3000 times larger in our cavity than in a Kerr-nonlinear cavity. Experiments evidencing this memory-enhanced bandwidth across two decades are presented. As an extension of our results, we numerically demonstrate an order-of-magnitude enhancement in energy harvesting thanks to a nonlinearity with memory.

Fractional-order (FO) chaotic systems exhibit richer and more complex dynamic behaviors compared to integer-order ones. This inherent richness and complexity enhance the security of FO chaotic systems against various attacks in image cryptosystems. In the present study, a comprehensive examination of the dynamical characteristics of the fractional-order Arneodo (FOAR) system with cubic nonlinearity is conducted. This investigation involves the analysis of phase planes, bifurcation diagrams, Lyapunov exponential spectra, and spectral entropy. Numerical studies show that the Arneodo chaotic system exhibits chaotic behavior when the lowest fractional-order (FO) value is set to 0.55. In this context, the aim is to securely encrypt biomedical images based on the Arneodo chaotic system with the lowest FO value using the Nvidia Jetson Nano development board. However, though the lowest FO system offers enhanced security in biomedical image encryption due to its richer dynamic behaviors, it necessitates careful consideration of the trade-off between high memory requirements and increasing complexity in encryption algorithms. Within the scope of the study, a novel random number generator (RNG) is designed using the FOAR chaotic system. The randomness of the random numbers is proven by using internationally accepted NIST 800-22 and ENT test suites. A biomedical image encryption application is developed using pseudo-random numbers. The images obtained as a result of the application are evaluated with tests such as histogram, correlation, differential attack, and entropy analyses. As a result of the study, it has been shown that encryption and decryption of biomedical images can be successfully performed on a mobile Nvidia Jetson Nano development card in a secure and fast manner.

5 - Nonlinear terahertz photonics

Intelligent home products have serious information security risks, threatening the privacy of users. In this paper, a method of password protection using hyper-chaos based one-way hash function and secure information transmission method based on spatiotemporal chaos are proposed. The proposed method creates a unidirectional hash function using the delay induced hyper-chaotic system and the key stream iteration to protect user password and to realize user authentication. At the same time, the chaotic time series generated by the one way coupled map lattice system is used to encrypt the plaintext information for the data secure communication, which increases the security of the intelligent home system. An intelligent home system prototype is built based on a Zigbee network, cloud server, and Android system.

We present a new application of optical coherence tomography (OCT), widely used in biomedical imaging, to flow analysis in near-wall hydrodynamics for marine research. This unique capability, called OCT micro-particle image velocimetry, provides a high-resolution view of microscopic flow phenomena and measurement of flow statistics within the first millimeter of a boundary layer. The technique is demonstrated in a small flow cuvette and in a water tunnel.

All-optical limiting devices are based on materials enabling light to control light, possessing a nonlinear optical response, and are reviving their popularity. One-dimensional photonic crystals (1 D PhC) are an auspicious platform for achieving novel optical limiters functioning for remarkably low limiting threshold and high damage threshold over a wider regime. 1 D PhC, a periodic nanostructure with a refractive index distribution along one direction, has been widely investigated by researchers. However, their utility to limit the high-intensity radiation to protect sophisticated optical sensors and devices is scarce in the research field. An overview of the numerically simulated, mathematically modeled, theoretically proposed, and experimentally realized 1 D PhC reflective optical limiters are provided here. This review focuses on the limited but noteworthy scrutiny of 1 D photonic crystal-based optical limiters using rare earth metals, nanocomposites, semiconductors, and phase-changing materials as defect layers. Highlights A reliable 1D PhC reflective optical limiter is resistant to laser induced damages. Limiter mechanism relies on creation of nonlinear localized modes. 1D PhC optical limiter reflects high power incident beams for a broader frequency window. Reflection based limiters are applicable for arbitrary direction of incidence.

Linear and nonlinear optical waveguiding in bio-inspired peptide nanotubes

Polarization phase gate and three-photon GHZ state using coherently enhanced Kerr nonlinearity