All-dielectric metalens based on the transmission phase was designed, which can uniformly shape a beam with a uniform energy distribution. The problems and related fixes for maintaining beam homogeneity and broad divergence angle simultaneously at 940 nm are explained. In order to solve the problem of wavefront shaping, based on the iterative design principle of complex surfaces such as freeform surfaces, a design scheme to shape the incident wavefront into 80° divergence angle wavefront was proposed. An effective, polarization-independent silicon nanopillar element is built based on the effective dielectric theory, and instead of using the conventional step size selection method, the size of each nanopillar is determined by the phase diameter function, covering the phase tuning from 0 to 2π.
Metalenses based on all-dielectric metasurfaces plays an important role in microscopic imaging, machine vision and holographic imaging. Chromatic aberration correction is an important factor that imaging devices. In this work, we propose an transmission achromatic metalens that can operate over a broad band of wavelengths. Based on the principle of phase compensation, the finite-difference time-domain method is used to calculate the wavefront of light for the design of the nano-units in the metalens with eliminating chromatic aberration. In the whole incident spectrum of visible light from 425 nm to 625 nm, The maximum focal shift of the achromatic metalens is about 7.9 %.And the average efficiency of the metalens with a numerical aperture of 0.6 is about 42 % in the wavelength band.
Large angle beam splitter grating is an important optical element but the current design methods are mostly based on the scalar diffraction theory based on Thin Element Approximation approximation, which is difficult to evaluate and calculate well when large angle beam splitting is involved. In this work, a method combining finite difference time domain method with adjoint optimization is proposed. Each iteration only needs two electromagnetic simulations to obtain the gradient distribution of the grating structure region. Using this method, a 1×5 beam splitting grating with a splitting angle of 10 degrees is designed. The final uniformity error is 3.7%, and the total diffraction efficiency is 86.6%. For the two-dimensional splitter , a 3×5 beam splitting grating with a diffraction full angle of 82.4×14 degrees is designed. Under the condition of large angle beam splitting, good uniformity error can still be maintained, and the final uniformity error reaches 23.1%.
Surface plasmon polaritons can manipulate and transmit light fields at the nanoscale, offering a wide range of applications in areas such as optoelectronic detection, optical filtering, novel light sources, and biosensing. This study investigated the transmission enhancement characteristics of conventional nanohole arrays through finite-difference time-domain (FDTD) simulations. Additionally, T-shaped metal nanoholes are designed based on the distinct spectral transmission properties of rectangular holes under varying polarized light conditions. Research has demonstrated that compared with their rectangular counterparts, T-shaped metal nanoholes exhibit polarization selectivity and sharper transmission spectra. Furthermore, this study investigated the impact of different components within the structure of T-shaped metal nanoholes on light field modulation by analyzing the electric field distribution. Finally, the influence of various parameters, such as the period, film thickness, and hole size, on the transmission spectrum of T-shaped metal nanoholes is investigated.
The Hall-effect metasurface described in this paper uses a combination of Pancharatnam-Berry ( PB ) phase and geometric phase to achieve independent phase control of different spin states. According to the established vector diffraction rigorous coupled wave model, the genetic algorithm is used to optimize the phase distribution of two different shaping effects. Then, different shaping functions are integrated into one device through the arrangement of metasurface microstructure units. By manipulating the polarization chirality of the incident light, the focusing and wavefront shaping of different spin-state photons can be realized at the same time, and two coaxially distributed composite spots can be obtained to achieve the purpose of multi-dimensional shaping of far-field spin-state photons. By this method, the central beam with better flat-top effect and the annular spot with larger radius can be obtained. The designed diffraction efficiency is greater than 90% and the spot uniformity is less than 15%. The welded products have both the smooth surface of semiconductor laser welding and the high aspect ratio of fiber laser welding.
High resolution and high precision polymer nanostructures has unique chemical and physical properties, playing an important role in nano-optics, nano-photonics, and high sensitivity biological detection. This paper demonstrated a novel fabrication method of biological detection chip based on polymer nanostructures via nanoimprint lithography. High precision nanostructures such as nanopillar arrays were prepared on chip film via nanoimprint lithography. The polymer nanostructures were used to enhance adhesion to cancer cells, which is low-cost and suitable for mass production. The replication polymer was biocompatibility materials that has no effect on cells. The experiment results show that the nanopillar arrays chip can adhere lung cancer cells in the size of 10-15 μm to achieve the purpose of filtering and detecting cells. Results of the experiments show that this new biological detection chip has potential applications of cancer detection, targeted therapy, food safety testing, and environmental monitoring.
An investigation on hybrid graphene-metal structure patch antenna has been carried out in the presented paper. The microwave radiation performance of the antenna is controlled by the optical tuning characteristic of graphene. The surface conductivity of graphene is changed, when variation of chemical potential is happened which can be regulated by an exterior light field. With simulations, the S11 coefficient of antenna is changed with a maximum of 32.2 dB when the chemical potential of graphene varies from 0 eV to 1 eV. The effect of different structure parameters, such as metal radiating patch sizes and graphene film widths, on the S11 coefficient in the graphene based antenna is further analyzed by simulations. With experiments, the measured S11 coefficient decreases gradually with optical intensity increases when using communication light with the wavelength of 1550 nm as modulation light. When the optical intensity of the communication light varieties from 0 mW to 25 mW, the S11 coefficient of the microwave is changed from -18.7 dB to -19 dB and the modulation depth is 0.3 dB. The results demonstrate the proposed method is a good candidate for modulating microwave directly by communication light.
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