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Here we demonstrate an active method which pioneers in utilizing a combination of a spatial frequency shift and a Stokes frequency shift to enable wide-field far-field subdiffraction imaging. A fluorescent nanowire ring acts as a localized source and is combined with a film waveguide to produce omnidirectional illuminating evanescent waves. Benefitting from the high wave vector of illumination, the high spatial frequencies of an object can be shifted to the passband of a conventional imaging system, contributing subwavelength spatial information to the far-field image. A structure featuring 70-nm-wide slots spaced 70 nm apart has been resolved at a wavelength of 520 nm with a 0.85 numerical aperture standard objective based on this method. The versatility of this approach has been demonstrated by imaging integrated chips, Blu-ray DVDs, biological cells, and various subwavelength 2D patterns, with a viewing area of up to 1000  μm^{2}, which is one order of magnitude larger than the previous far-field and full-field nanoscopy methods. This new resolving technique is label-free, is conveniently integrated with conventional microscopes, and can potentially become an important tool in cellular biology, the on-chip industry, as well as other fields requiring wide-field nanoscale visualization.

Wide field‐of‐view (FOV), label‐free, super‐resolution imaging is demonstrated using a specially designed waveguide chip that can illuminate a sample with multicolor evanescent waves travelling along different directions. The method is enabled by a polymer fluorescent film that emits over a broad wavelength range. Its polygonal geometry ensures coverage over all illumination directions, enabling high‐fidelity image reconstruction while minimizing distortion and image blurring. By frequency shifting and iterative stitching of different spatial frequencies in Fourier space, the reconstruction of 2D samples is achieved without distortion over wide FOVs. The fabrication process is facile and compatible with conventional semiconductor‐fabrication methods. The super‐resolution chip (SRC) can thus be produced with high yield, offering opportunities for potential conjunction of super‐resolution techniques integrated optical circuits or for the development of single‐use diagnostic kits.

Super-resolution microscopy is typically not applicable to in situ imaging through a narrow channel due to the requirement for complex optics. Although multimode fibres (MMFs) have emerged as a potential platform for cost-effective and precise endoscopic imaging, they suffer from extreme sensitivity to bending and other external conditions. Here we demonstrate imaging through a single thin MMF for in vivo light-field encoded imaging with subcellular resolution. We refer to the technique as spatial-frequency tracking adaptive beacon light-field-encoded (STABLE) endoscopy. Spatial-frequency beacon tracking provides up to 1 kHz disorder tracking frequency, thus ensuring stable imaging through long-haul MMFs under fibre bending and various operating conditions. The full-vector modulation and fluorescence emission difference are combined to enhance the imaging signal-to-noise ratio and achieve a subdiffraction resolution of 250 nm. We integrate STABLE in a white-light endoscope and demonstrate cross-scale imaging in a bronchus model and in vivo imaging in mice models. The high-resolution and resilience to observation in a minimally invasive manner paves the way to the expansion of MMF in endoscopy to the study of disease mechanisms in biomedical sciences and clinical studies.

In this letter, we propose a broadband absorber with high efficiency by an atomic layer depositing nanometer iridium (Ir) film onto a porous anodic alumina (PAA) template. The average absorption is able to achieve as high as 93.4% from 400 to 1100 nm and the absorption efficiency can reach up to 96.8% for the improved structure of the quadrangular frustum pyramid array. Not only the hexagonal latticed structures of the PAA template but also many similar structures based on gratings or holes with the square latticed or other latticed mode can realize the broadband high absorption efficiency. The light absorbed within the Ir/Glass interface and the sidewalls of PAA by the light funneling effect both contribute to the broadband absorption with high efficiency. This absorber, described in this paper, can be manufactured with a low-cost and large-area manner and has potential applications in fields of light harvesting, imaging, etc.

We present a novel design of multi-color (405 nm, 532 nm and 780 nm) illuminated silicon nitride (Si 3 N 4 ) waveguide platform for two-dimensional label-free super-resolution imaging based on frequency shifting and Gerchberg-Saxton algorithm reconstruction. We simulated the light propagating process and imaging process, indicating the capability of super-resolution imaging with high signal-to-noise ratio by mode control in the waveguide. Dispersion of the sample was also analysed for multi-wavelength illumination. The Si 3 N 4 waveguide platform provides a convenient and high-quality illumination approach for frequency-shift-based superresolution imaging.

As an ideal miniaturized light source, wavelength-tunable nanolasers capable of emitting a wide spectrum stimulate intense interests for on-chip optoelectronics, optical communications, and spectroscopy. However, realization of such devices remains a major challenge because of extreme difficulties in achieving continuously reversibly tunable gain media and high quality (Q)-factor resonators on the nanoscale simultaneously. Here, exploiting single bandgap-graded CdSSe NWs and a Fabry–Pérot/whispering gallery mode (FP/WGM) coupling cavity, a free-standing fiber-integrated reversibly wavelength-tunable nanolaser covering a 42 nm wide spectrum at room temperature with high stability and reproducibility is demonstrated. In addition, a 1.13 nm tuning spectral resolution is realized. The substrate-free device design enables integration in optical fiber communications and information. With reversible and wide, continuous tunability of emission color and precise control per step, our work demonstrates a general approach to nanocavity coupling affording high Q-factors, enabling an ideal miniaturized module for a broad range of applications in optics and optoelectronics, with optical fiber integration.

In this Letter, we show how to obtain high-contrast wide-field evanescent wave illuminated subdiffraction imaging through controlling nanoscale light-matter interaction. The light coupling, propagation, and far-field imaging processes show strong polarization selectivity and film quality dependence, which is used to improve the image-contrast-to-noise ratio (CNR) and to enlarge the field of view (FOV). We demonstrate experimentally high CNR subdiffraction imaging with lateral resolution of 122 nm and FOV of thousands of micrometers square.