Near-field plates with the capabilities of modulating the near-field pattern and forcing the incident wave to a subwavelength spot have been experimentally investigated at microwave wavelengths.Their superlensing prop...Near-field plates with the capabilities of modulating the near-field pattern and forcing the incident wave to a subwavelength spot have been experimentally investigated at microwave wavelengths.Their superlensing properties result from the radiationless electromagnetic interference.However, the material's loss and limitations of state-of-the-art nanofabricating technology pose great challenges to scale down the microwave near-field plates to the infrared or optical region.In this paper, a related but alternative approach based on metasurface is introduced which breaks the near-field diffraction limit at mid-infrared region(10.6 μm).The metasurface consists of periodic arrangement of chromium dipolar antennas with the same geometry but spatially varying orientations, which plays the dual roles in achieving the prescribed amplitude modulation and the abrupt π phase change between the subwavelength neighboring elements.As a result, a two dimensional subdiffraction focus as small as 0.037λ~2 at ~0.15λ above the metasurface is presented.In addition, the broadband response and ease fabrication bridge the gap between the theoretical investigation and valuable applications, such as near-field data storage, subdiffraction imaging and nanolithography.展开更多
The properties of the photonic nanojet generated by a two-layer dielectric microsphere are studied. Simulation results indicate that this novel structure can generate a photonic nanojet outside its volume when the ref...The properties of the photonic nanojet generated by a two-layer dielectric microsphere are studied. Simulation results indicate that this novel structure can generate a photonic nanojet outside its volume when the refractive index contrast relative to the background medium is higher than 2：1 in the condition of plane wave incidence. When the refractive index is smaller than 2, we show that an ultralong nanojet generated by the two-layer hemisphere has an extension of 28.2 wavelengths, and compared with the homogeneous dielectric hemisphere, it has superior performance in jet length and focal distance. Its dependence on the configuration and refractive index is investigated numerically. According to the simulation of the two-layer dielectric microsphere, a photonic nanojet with a full width at half maximum（FWHM） less than 1/2 wavelength is obtained and the tunable behaviors of the photonic nanojet are demonstrated by changing the reflective indices of the material or radius contrast ratio.展开更多
We demonstrate the spectroscopy of incoherent light with subdiffraction resolution.In a proof-of-principle experiment,we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the dif...We demonstrate the spectroscopy of incoherent light with subdiffraction resolution.In a proof-of-principle experiment,we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the diffraction limit.The two sources mimic a planetary system,with a brighter source for the star and a dimmer one for the planet.Acquiring spectral information about the secondary source is difficult because the two images have a substantial overlap.This limitation is solved by leveraging a structured measurement based on spatial-mode demultiplexing,where light is first sorted in its Hermite–Gaussian components in the transverse field then measured by photon detection.This allows us to effectively decouple the photons coming from the two sources.An application is suggested to enhance the exoplanets’atmosphere spectroscopy.A number of experiments of super-resolution imaging based on spatial demultiplexing have been conducted in the past few years,with promising results.Here,for the first time to the best of our knowledge,we extend this concept to the domain of spectroscopy.展开更多
Mesoporous silica nanoparticles(MSNPs)are promising nanomedicine vehicles due to their biocompatibility and ability to carry large cargoes.It is critical in nanomedicine development to be able to map their uptake in c...Mesoporous silica nanoparticles(MSNPs)are promising nanomedicine vehicles due to their biocompatibility and ability to carry large cargoes.It is critical in nanomedicine development to be able to map their uptake in cells,including distinguishing surface associated MSNPs from those that are embedded or internalized into cells.Conventional nanoscale imaging techniques,such as electron and fluorescence microscopies,however,generally require the use of stains and labels to image both the biological material and the nanomedicines,which can interfere with the biological processes at play.We demonstrate an alternative imaging technique for investigating the interactions between cells and nanostructures,scatteringtype scanning near-field optical microscopy(s-SNOM).s-SNOM combines the chemical sensitivity of infrared spectroscopy with the nanoscale spatial resolving power of scanning probe microscopy.We use the technique to chemically map the uptake of MSNPs in whole human glioblastoma cells and show that the simultaneously acquired topographical information can provide the embedding status of the MSNPs.We focus our imaging efforts on the lamellipodia and filopodia structures at the peripheries of the cells due to their significance in cancer invasiveness.展开更多
基金supported by the National Natural Science Funds (61575032)
文摘Near-field plates with the capabilities of modulating the near-field pattern and forcing the incident wave to a subwavelength spot have been experimentally investigated at microwave wavelengths.Their superlensing properties result from the radiationless electromagnetic interference.However, the material's loss and limitations of state-of-the-art nanofabricating technology pose great challenges to scale down the microwave near-field plates to the infrared or optical region.In this paper, a related but alternative approach based on metasurface is introduced which breaks the near-field diffraction limit at mid-infrared region(10.6 μm).The metasurface consists of periodic arrangement of chromium dipolar antennas with the same geometry but spatially varying orientations, which plays the dual roles in achieving the prescribed amplitude modulation and the abrupt π phase change between the subwavelength neighboring elements.As a result, a two dimensional subdiffraction focus as small as 0.037λ~2 at ~0.15λ above the metasurface is presented.In addition, the broadband response and ease fabrication bridge the gap between the theoretical investigation and valuable applications, such as near-field data storage, subdiffraction imaging and nanolithography.
基金Project supported by State Key Laboratory of Optical Technologies on Nano-Fabrication and Micro-Engineering,Institute of Optics and Electronics,Chinese Academy of SciencesSichuan Provincial Department of Education,China(Grant No.16ZA0047)+1 种基金the State Key Laboratory of Metastable Materials Science and Technology,Yansan University,China(Grant No.201509)the Large Precision Instruments Open Project Foundation of Sichuan Normal University,China(Grant Nos.DJ2015-57,DJ2015-58,DJ2015-60,DJ2016-58,and DJ2016-59)
文摘The properties of the photonic nanojet generated by a two-layer dielectric microsphere are studied. Simulation results indicate that this novel structure can generate a photonic nanojet outside its volume when the refractive index contrast relative to the background medium is higher than 2：1 in the condition of plane wave incidence. When the refractive index is smaller than 2, we show that an ultralong nanojet generated by the two-layer hemisphere has an extension of 28.2 wavelengths, and compared with the homogeneous dielectric hemisphere, it has superior performance in jet length and focal distance. Its dependence on the configuration and refractive index is investigated numerically. According to the simulation of the two-layer dielectric microsphere, a photonic nanojet with a full width at half maximum（FWHM） less than 1/2 wavelength is obtained and the tunable behaviors of the photonic nanojet are demonstrated by changing the reflective indices of the material or radius contrast ratio.
基金European Commission (PE0000023-NQSTI)Ministero dell'Universitàe della Ricerca (QUEXO2022NZP4T3)Italian Space Agency (Subdiffraction Quantum Imaging SQI 2023-13-HH.0)。
文摘We demonstrate the spectroscopy of incoherent light with subdiffraction resolution.In a proof-of-principle experiment,we analyze the spectrum of a pair of incoherent pointlike sources whose separation is below the diffraction limit.The two sources mimic a planetary system,with a brighter source for the star and a dimmer one for the planet.Acquiring spectral information about the secondary source is difficult because the two images have a substantial overlap.This limitation is solved by leveraging a structured measurement based on spatial-mode demultiplexing,where light is first sorted in its Hermite–Gaussian components in the transverse field then measured by photon detection.This allows us to effectively decouple the photons coming from the two sources.An application is suggested to enhance the exoplanets’atmosphere spectroscopy.A number of experiments of super-resolution imaging based on spatial demultiplexing have been conducted in the past few years,with promising results.Here,for the first time to the best of our knowledge,we extend this concept to the domain of spectroscopy.
基金support from EPSRC(EP/N509486/1,EP/R513052/1).J.M.T.acknowledges an EPSRC funded CDT in Neurotechnology for PhD fundingA.P acknowledges an Imperial College Research Fellowship for funding.C.C.P.acknowledges a Cancer Research UK grant(C68186/A28503).
文摘Mesoporous silica nanoparticles(MSNPs)are promising nanomedicine vehicles due to their biocompatibility and ability to carry large cargoes.It is critical in nanomedicine development to be able to map their uptake in cells,including distinguishing surface associated MSNPs from those that are embedded or internalized into cells.Conventional nanoscale imaging techniques,such as electron and fluorescence microscopies,however,generally require the use of stains and labels to image both the biological material and the nanomedicines,which can interfere with the biological processes at play.We demonstrate an alternative imaging technique for investigating the interactions between cells and nanostructures,scatteringtype scanning near-field optical microscopy(s-SNOM).s-SNOM combines the chemical sensitivity of infrared spectroscopy with the nanoscale spatial resolving power of scanning probe microscopy.We use the technique to chemically map the uptake of MSNPs in whole human glioblastoma cells and show that the simultaneously acquired topographical information can provide the embedding status of the MSNPs.We focus our imaging efforts on the lamellipodia and filopodia structures at the peripheries of the cells due to their significance in cancer invasiveness.
