High-Refractive-Index Chip with Periodically Fine-Tuning Gratings for Tunable Virtual-Wavevector Spatial Frequency Shift Universal Super-Resolution Imaging.

Mingwei Tang,Xiaowei Liu,Qianwei Zhang,Dehao Ye,Qing Yang,Weidong Shen,Yaoguang Ma,Yubing Han,Clemens F Kaminski,Chenlei Pang,Xu Liu

doi:10.1002/advs.202103835

Abstract

Continued research in fields such as materials science and biomedicine requires the development of a super‐resolution imaging technique with a large field of view (FOV) and deep subwavelength resolution that is compatible with both fluorescent and nonfluorescent samples. Existing on‐chip super‐resolution methods exclusively focus on either fluorescent or nonfluorescent imaging, and, as such, there is an urgent requirement for a more general technique that is capable of both modes of imaging. In this study, to realize labeled and label‐free super‐resolution imaging on a single scalable photonic chip, a universal super‐resolution imaging method based on the tunable virtual‐wavevector spatial frequency shift (TVSFS) principle is introduced. Using this principle, imaging resolution can be improved more than threefold over the diffraction limit of a linear optical system. Here, diffractive units are fabricated on the chip's surface to provide wavevector‐variable evanescent wave illumination, enabling tunable spatial frequency shifts in the Fourier space. A large FOV and resolutions of λ/4.7 and λ/7.1 were achieved for label‐free and fluorescently labeled samples using a gallium phosphide (GaP) chip. With its large FOV, compatibility with different imaging modes, and monolithic integration, the proposed TVSFS chip may advance fields such as cell engineering, precision industry inspection, and chemical research.

Highlights

The spatial resolution of conventional microscopy is limited by optical diffraction
To experimentally demonstrate the tunable virtual-wavevector spatial frequency shift (TVSFS) super-resolution imaging, we developed a fabrication process for the scalable chip with various controllable illumination wavevectors
We have demonstrated a universal super-resolution imaging method based on the tunable virtualwavevector spatial frequency shift effect, which we have termed as ‘tunable virtual-wavevector spatial frequency shift’ (TVSFS)

Summary

Introduction

The advent of fluorescencebased super-resolution microscopy opens the way for far-field detection in discerning nanometer-scale details, such as stimulated emission depletion microscopy(STED)[1,2], single-molecule localization microscopy(SMLM)[3], and MINFLUX4,5. Such methods break the diffraction limit in the spatial domain by shrinking the point-spread function of the optical system. By reconstructing in the Fourier space, the detection spatial-frequency aperture (that is, the transfer function) can be expanded It can provide high-speed, high-resolution, and wide-field imaging. Compared with STED and SMLM methods, which rely on fluorescence with specific characters, the SFS method is a universal method compatible with both label-free and labeled imaging

Methods

Results

Conclusion