With the rapid development of sensor networks, machine vision faces the problem of storing and computing massive data. The human visual system has a very efficient information sense and computation ability, which has enlightening significance for solving the above problems in machine vision. This review aims to comprehensively summarize the latest advances in bio-inspired image sensors that can be used to improve machine-vision processing efficiency. After briefly introducing the research background, the relevant mechanisms of visual information processing in human visual systems are briefly discussed, including layer-by-layer processing, sparse coding, and neural adaptation. Subsequently, the cases and performance of image sensors corresponding to various bio-inspired mechanisms are introduced. Finally, the challenges and perspectives of implementing bio-inspired image sensors for efficient machine vision are discussed.

Metasurface-based imaging has attracted considerable attention owing to its compactness, multifunctionality, and subwavelength coding capability. With the integration of computational imaging techniques, researchers have actively explored the extended capabilities of metasurfaces, enabling a wide range of imaging methods. We present an overview of the recent progress in metasurface-based imaging techniques, focusing on the perspective of computational imaging. Specifically, we categorize and review existing metasurface-based imaging into three main groups, including (i) conventional metasurface design employing canonical methods, (ii) computation introduced independently in either the imaging process or postprocessing, and (iii) an end-to-end computation-optimized imaging system based upon metasurfaces. We highlight the advantages and challenges associated with each computational metasurface-based imaging technique and discuss the potential and future prospects of the computational boosted metaimager.

Near-infrared (NIR) light has shown great potential for military and civilian applications owing to its advantages in the composition of sunlight, invisibility to human eyes, deeper penetration into biological tissues, and low optical loss in optical fibers. Therefore, organic optoelectronic materials that can absorb or emit NIR light have aroused great scientific interest in basic science and practical applications. Based on these NIR organic optoelectronic materials, NIR optoelectronic devices have been greatly improved in performance and application. In this review, the representative NIR organic optoelectronic materials used in organic solar cells, organic photodetectors, organic light-emitting diodes, organic lasers, and organic optical waveguide devices are briefly introduced, and the potential applications of each kind of device are briefly summarized. Finally, we summarize and take up the development of NIR organic optoelectronic materials and devices.

We review the physics and some applications of photonic structures designed for the realization of strong nonlinear chiroptical response. We pay much attention to the recent strategy of utilizing different types of optical resonances in metallic and dielectric subwavelength structures and metasurfaces, including surface plasmon resonances, Mie resonances, lattice-guided modes, and bound states in the continuum. We summarize earlier results and discuss more recent developments for achieving large circular dichroism combined with the high efficiency of nonlinear harmonic generation.

Photoacoustic imaging (PAI), recognized as a promising biomedical imaging modality for preclinical and clinical studies, uniquely combines the advantages of optical and ultrasound imaging. Despite PAI’s great potential to provide valuable biological information, its wide application has been hindered by technical limitations, such as hardware restrictions or lack of the biometric information required for image reconstruction. We first analyze the limitations of PAI and categorize them by seven key challenges: limited detection, low-dosage light delivery, inaccurate quantification, limited numerical reconstruction, tissue heterogeneity, imperfect image segmentation/classification, and others. Then, because deep learning (DL) has increasingly demonstrated its ability to overcome the physical limitations of imaging modalities, we review DL studies from the past five years that address each of the seven challenges in PAI. Finally, we discuss the promise of future research directions in DL-enhanced PAI.

Different from single and static photonic materials, dynamically responsive materials possess numerous advantages, such as being multifunctional, dynamically responsive, and able to provide multiple channels within spatially limited platforms, thus exhibiting great potential for application in the color-on-demand areas, including imaging, optical displays, anticounterfeiting, and encoding. Photonic functional metal–organic frameworks (MOFs), with highly designable framework structures and varieties of optical functional building units, possess broad research and application prospects in the field of photonics, which make it possible to design a promising platform with multifunctional and integrated photonic performance. In this review, beyond the preparation strategies of stimuli-responsive photonic MOFs, we also summarize the stimuli-responsive photonic MOFs regarding several most representative types of external stimuli (such as light, gas, pressure, and polarization). As shown, external stimulation endows the stimuli-responsive photonic MOFs with intriguing regulatable photonic properties: intensive and tunable emission, multiphoton-excitable luminescence, nonlinear optical, circularly polarized luminescence, lasing, etc. Furthermore, their advanced representative applications, such as information encryption and anticounterfeiting display, biological imaging, chemosensing, and others, are also reviewed. The challenges are proposed and the prospects are addressed.

We review the recent biomedical detection developments of scanning near-field optical microscopy (SNOM), focusing on scattering-type SNOM, atomic force microscope-based infrared spectroscopy, peak force infrared microscopy, and photo-induced force microscopy, which have the advantages of label-free, noninvasive, and specific spectral recognition. Considering the high water content of biological samples and the strong absorption of water by infrared waves, we divide the relevant research on these techniques into two categories: one based on a nonliquid environment and the other based on a liquid environment. In the nonliquid environment, the chemical composition and structural information of biomedical samples can be obtained with nanometer resolution. In the liquid environment, these techniques can be used to monitor the dynamic chemical reaction process and track the process of chemical composition and structural change of single molecules, which is conducive to exploring the development mechanism of physiological processes. We elaborate their experimental challenges, technical means, and actual cases for three microbiomedical samples (including biomacromolecules, cells, and tissues). We also discuss the prospects and challenges for their development. Our work lays a foundation for the rational design and efficient use of near-field optical microscopy to explore the characteristics of microscopic biology.

The optical angular momentum is ubiquitous to the science of light, especially whenever the polarization state and the spatial distribution of the phase are involved, which are most often associated with the spin and orbital parts of the total angular momentum, respectively. Notably, the independent introduction of these two contributions to the total optical angular momentum was accompanied by suggestions regarding the possible detection of their mechanical effects using a torsion pendulum. Today, the classical and quantum mechanical aspects of spin and orbital angular momentum of light and their mutual coupling remain active research topics offering exciting perspectives for photonic technologies. Our brief historical overview shows how the torsion pendulum has accompanied scientific advances on mechanical effects based on the angular degrees of freedom of light since Beth’s pioneering contribution published in 1935.

Lithium niobate (LN) thin film has received much attention as an integrated photonic platform, due to its rich and great photoelectric characteristics, based on which various functional photonic devices, such as electro-optic modulators and nonlinear wavelength converters, have been demonstrated with impressive performance. As an important part of the integrated photonic system, the long-awaited laser and amplifier on the LN thin-film platform have made a series of breakthroughs and important progress recently. In this review paper, the research progress of lasers and amplifiers realized on lithium niobate thin film platforms is reviewed comprehensively. Specifically, the research progress on optically pumped lasers and amplifiers based on rare-earth ions doping of LN thin films is introduced. Some important parameters and existing limitations of the current development are discussed. In addition, the implementation scheme and research progress of electrically pumped lasers and amplifiers on LN thin-film platforms are summarized. The advantages and disadvantages of optically and electrically pumped LN thin film light sources are analyzed. Finally, the applications of LN thin film lasers and amplifiers and other on-chip functional devices are envisaged.

Visible light communication (VLC) is an emerging technology employing light-emitting diodes (LEDs) to provide illumination and wireless data transmission simultaneously. Harnessing cost-efficient printable organic LEDs (OLEDs) as environmentally friendly transmitters in VLC systems is extremely attractive for future applications in spectroscopy, the internet of things, sensing, and optical ranging in general. Here, we summarize the latest research progress on emerging semiconductor materials for LED sources in VLC, and highlight that OLEDs based on nontoxic and cost-efficient organic semiconductors have great opportunities for optical communication. We further examine efforts to achieve high-performance white OLEDs for general lighting, and, in particular, focus on the research status and opportunities for OLED-based VLC. Different solution-processable fabrication and printing strategies to develop high-performance OLEDs are also discussed. Finally, an outlook on future challenges and potential prospects of the next-generation organic VLC is provided.