Chaos in nonlinear dynamical systems is featured with irregular appearance and with high sensitivity to initial conditions. Near-infrared light chaos based on semiconductor lasers has been extensively studied and has enabled various applications. Here, we report a fully-developed hyperchaos in the mid-infrared regime, which is produced from interband cascade lasers subject to the external optical feedback. Lyapunov spectrum analysis demonstrates that the chaos exhibits three positive Lyapunov exponents. Particularly, the chaotic signal covers a broad frequency range up to the GHz level, which is two to three orders of magnitude broader than existed mid-infrared chaos solutions. The interband cascade lasers produce either periodic oscillations or low-frequency fluctuations before bifurcating to hyperchaos. This hyperchaos source is valuable for developing long-reach secure optical communication links and remote chaotic Lidar systems, taking advantage of the high-transmission windows of the atmosphere in the mid-infrared regime.

Nanophotonic devices with high densities are extremely attractive because they can potentially merge photonics and electronics at the nanoscale. However, traditional integrated photonic circuits are designed primarily by manually selecting parameters or employing semi‐analytical models. Limited by the small parameter search space, the designed nanophotonic devices generally have a single function, and the footprints reach hundreds of microns. Recently, novel ultra‐compact nanophotonic devices with digital structures were proposed. By applying inverse design algorithms, which can search the full parameter space, the proposed devices show extremely compact footprints of a few microns. The results from many groups imply that digital nanophotonics can achieve not only ultra‐compact single‐function devices but also miniaturized multi‐function devices and complex functions such as artificial intelligence operations at the nanoscale. Furthermore, to balance the performance and fabrication tolerances of such devices, researchers have developed various solutions, such as adding regularization constraints to digital structures. We believe that with the rapid development of inverse design algorithms and continuous improvements to the nanofabrication process, digital nanophotonics will play a key role in promoting the performance of nanophotonic integration. In this review, we uncover the exciting developments and challenges in this field, analyse and explore potential solutions to these challenges and provide comments on future directions in this field.

In environments where traditional fiber optic cables are impractical, free-space optical communications offer a promising solution for transmitting large amounts of data, especially in the mid-infrared wavelength range. Despite the advantages of minimal atmospheric interference and stable signals, the vulnerability of wireless optical communications to eavesdropping poses a significant challenge. This study addresses this challenge by demonstrating a method for privately transmitting optical data using photonic chaos from distributed feedback quantum cascade lasers operating at 9.3 µm. Signal processing techniques are applied to enhance the quality of the transmission over distances exceeding 30 m, accompanied by a comprehensive analysis of the photonic chaos complexity to ensure data confidentiality. These findings mark a significant advancement in developing private communications systems within the thermal atmospheric window, with a substantially reduced risk of interception by adversaries. The research not only contributes to secure communications but also has potential implications for enhancing security of data transmission in challenging environments, impacting various industries and applications.

Most multispectral compatible infrared camouflage devices primarily focus on achieving low emissivity but neglect environmental emissivity matching when environmental emissivity exceeds that of the devices, this creates a "low-emissivity exposure" risk. To address this issue, we develop a tunable multispectral compatible infrared camouflage device using phase change material In 3 SbTe 2 (IST). Simulation and experimental results demonstrate that in both the amorphous (aIST) and crystalline (cIST) states, the device achieves simulated plant infrared camouflage and ultra-low emissivity infrared camouflage within the atmospheric window bands (3-5 µm and 8-14 µm). To address thermal management, it utilizes two non-atmospheric window bands (2.5-3 µm and 5-8 µm) for heat dissipation. Additionally, laser stealth is realized at three specific wavelengths (1.064 µm, 1.55 µm, and 10.6 µm). In the visible spectrum, high absorptivity enables effective visible light camouflage. Adjusting the geometric parameters of top layer structure enables color variation. This work not only highlights potential applications in reversible switching, reconfigurable imaging, and dynamic coding using IST but also offers an effective strategy to counter multispectral detection technology.

Metalens optical tweezers technology has several advantages for manipulating micro-nano particles and high integration. Here, we used particle swarm optimization (PSO) to design a novel metalens tweezer, which can get 3-dimensional trapping of particles. The numerical aperture (NA) of the metalens can reach 0.97 and the average focusing efficiency is 44%. Subsequently, we analyzed the optical force characteristics of SiO₂ particles with a radius of 350 nm at the focal point of the achromatic metalens. We found the average maximum force of SiO₂ particles in the x-direction and z-direction to be 0.88 pN and 0.72 pN, respectively. Compared with the dispersive metalens, it is beneficial in maintaining the constant of optical force, the motion state of trapped particles, and the stability of the trapping position.