41 research outputs found
Advancing nonlinear nanophotonics: harnessing membrane metasurfaces for third-harmonic generation and imaging
Dielectric metasurfaces are crucial for enhancing optical nonlinear generation, particularly membrane metasurfaces with multipolar resonances and compact size. Investigating silicon dimer-hole membrane metasurfaces, Rahmani, and Xu show how bound states in the continuum (BICs) can be formed and transformed into quasi-BICs by adjusting hole gaps. This innovation enables efficient conversion of infrared images to visible range, promising applications in nonlinear photonics and near-infrared imaging technologies
First realization of macroscopic Fourier ptychography for hundred-meter distance sub-diffraction imaging
Fourier ptychography (FP) imaging, drawing on the idea of synthetic aperture,
has been demonstrated as a potential approach for remote
sub-diffraction-limited imaging. Nevertheless, the farthest imaging distance is
still limited around 10 m even though there has been a significant improvement
in macroscopic FP. The most severely issue in increasing the imaging distance
is FoV limitation caused by far-field condition for diffraction. Here, we
propose to modify the Fourier far-field condition for rough reflective objects,
aiming to overcome the small FoV limitation by using a divergent beam to
illuminate objects. A joint optimization of pupil function and target image is
utilized to attain the aberration-free image while estimating the pupil
function simultaneously. Benefiting from the optimized reconstruction algorithm
which effectively expands the camera's effective aperture, we experimentally
implement several FP systems suited for imaging distance of 12 m, 90 m, and 170
m with the maximum synthetic aperture of 200 mm. The maximum imaging distance
and synthetic aperture are thus improved by more than one order of magnitude of
the state-of-the-art works with a fourfold improvement in the resolution. Our
findings demonstrate significant potential for advancing the field of
macroscopic FP, propelling it into a new stage of development
Physics-data-driven intelligent optimization for large-scale meta-devices
Meta-devices have gained significant attention and have been widely utilized
in optical systems for focusing and imaging, owing to their lightweight,
high-integration, and exceptional-flexibility capabilities. However, based on
the assumption of local phase approximation, traditional design method neglect
the local lattice coupling effect between adjacent meta-atoms, thus harming the
practical performance of meta-devices. Using physics-driven or data-driven
optimization algorithms can effectively solve the aforementioned problems.
Nevertheless, both of the methods either involve considerable time costs or
require a substantial amount of data sets. Here, we propose a
physics-data-driven approach based "intelligent optimizer" that enables us to
adaptively modify the sizes of the studied meta-atom according to the sizes of
its surrounding ones. Such a scheme allows to mitigate the undesired local
lattice coupling effect, and the proposed network model works well on thousands
of datasets with a validation loss of 3*10-3. Experimental results show that
the 1-mm-diameter metalens designed with the "intelligent optimizer" possesses
a relative focusing efficiency of 93.4% (as compared to ideal focusing) and a
Strehl ratio of 0.94. In contrast to the previous inverse design method, our
method significantly boosts designing efficiency with five orders of magnitude
reduction in time. Our design approach may sets a new paradigm for devising
large-scale meta-devices.Comment: manuscripts:19 pages, 4 figures; Supplementary Information: 11 pages,
12 figure
Improved spatiotemporal resolution of anti-scattering super-resolution label-free microscopy via synthetic wave 3D metalens imaging
Super-resolution (SR) microscopy has dramatically enhanced our understanding of biological processes. However, scattering media in thick specimens severely limits the spatial resolution, often rendering the images unclear or indistinguishable. Additionally, live-cell imaging faces challenges in achieving high temporal resolution for fast-moving subcellular structures. Here, we present the principles of a synthetic wave microscopy (SWM) to extract three-dimensional information from thick unlabeled specimens, where photobleaching and phototoxicity are avoided. SWM exploits multiple-wave interferometry to reveal the specimen’s phase information in the area of interest, which is not affected by the scattering media in the optical path. SWM achieves ~0.42 λ/NA resolution at an imaging speed of up to 106 pixels/s. SWM proves better temporal resolution and sensitivity than the most conventional microscopes currently available while maintaining exceptional SR and anti-scattering capabilities. Penetrating through the scattering media is challenging for conventional imaging techniques. Remarkably, SWM retains its efficacy even in conditions of low signal-to-noise ratios. It facilitates the visualization of dynamic subcellular structures in live cells, encompassing tubular endoplasmic reticulum (ER), lipid droplets, mitochondria, and lysosomes
Crosstalk-free achromatic full Stokes imaging polarimetry metasurface enabled by polarization-dependent phase optimization
Imaging polarimetry is one of the most widely used analytical technologies for object detection and analysis. To date, most metasurface-based polarimetry techniques are severely limited by narrow operating bandwidths and inevitable crosstalk, leading to detrimental effects on imaging quality and measurement accuracy. Here, we propose a crosstalk-free broadband achromatic full Stokes imaging polarimeter consisting of polarization-sensitive dielectric metalenses, implemented by the principle of polarization-dependent phase optimization. Compared with the single-polarization optimization method, the average crosstalk has been reduced over three times under incident light with arbitrary polarization ranging from 9 μm to 12 μm, which guarantees the measurement of the polarization state more precisely. The experimental results indicate that the designed polarization-sensitive metalenses can effectively eliminate the chromatic aberration with polarization selectivity and negligible crosstalk. The measured average relative errors are 7.08%, 8.62%, 7.15%, and 7.59% at 9.3, 9.6, 10.3, and 10.6 μm, respectively. Simultaneously, the broadband full polarization imaging capability of the device is also verified. This work is expected to have potential applications in wavefront detection, remote sensing, light-field imaging, and so forth
Taming the Electromagnetic Boundaries via Metasurfaces: From Theory and Fabrication to Functional Devices
As two-dimensional metamaterials, metasurfaces have received rapidly increasing attention from researchers all over the world. Unlike three-dimensional metamaterials, metasurfaces can be utilized to control the electromagnetic waves within one infinitely thin layer, permitting substantial advantages, such as easy fabrication, low cost, and high degree of integration. This paper reviews the history and recent development of metasurfaces, with particular emphasis on the theory and applications relating to the frequency response, phase shift, and polarization state control. Based on the current status of various applications, the challenges and future trends of metasurfaces are discussed
Meta-Chirality: Fundamentals, Construction and Applications
Chiral metamaterials represent a special type of artificial structures that cannot be superposed to their mirror images. Due to the lack of mirror symmetry, cross-coupling between electric and magnetic fields exist in chiral mediums and present unique electromagnetic characters of circular dichroism and optical activity, which provide a new opportunity to tune polarization and realize negative refractive index. Chiral metamaterials have attracted great attentions in recent years and have given rise to a series of applications in polarization manipulation, imaging, chemical and biological detection, and nonlinear optics. Here we review the fundamental theory of chiral media and analyze the construction principles of some typical chiral metamaterials. Then, the progress in extrinsic chiral metamaterials, absorbing chiral metamaterials, and reconfigurable chiral metamaterials are summarized. In the last section, future trends in chiral metamaterials and application in nonlinear optics are introduced