分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Using the SLS technique, the size distribution can be measured accurately when the Rayleigh-Gans-Debye approximation is valid for dilute homogenous spherical particles in dispersion. For the commercial samples, the static sizes are consistent with the sizes provided by supplier respectively. The values of root mean square radius of gyration measured using the Zimm plot and calculated using the commercial size distributions or size distributions measured using the SLS technique are consistent respectively. Based on the static size distribution, with one assumption between the static and hydrodynamic radii, the calculated and measured data of DLS are consistent very well at all the scattering angles investigated respectively. Using the static size information the dimensionless shape parameter is discussed, our results show that the shapes can not be determined based on the dimensionless shape parameter. Traditionally, the particle information: apparent hydrodynamic radius and polydispersity index are obtained from DLS by analyzing the deviations of the intensity-intensity autocorrelation function from an exponent function. Since the apparent hydrodynamic radius obtained using the Stokes-Einstein relation is an optical weighted average radius, it is an approximate value of mean hydrodynamic radius. And the polydispersity index is not relate to the width of hydrodynamic radius. Therefore the apparent hydrodynamic radius and polydispersity index cannot give an accurate description for size distribution.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： Photonic bandgap design is one of the most basic ways to effectively control the interaction between light and matter. However, the traditional photonic bandgap is always dispersive (blueshift with the increase of the incident angle), which is disadvantageous to the construction of wide-angle optical devices. Hypercrystal, that the photonic crystal with layered hyperbolic metamaterials (HMMs), can strongly modify the bandgap properties based on the anomalous wavevector dispersion of the HMM. Here, based on phase variation compensation between HMM and isotropic dielectric layers, we propose for the first time to design nonreciprocal and flexible photonic bandgaps using magneto-optical HMMs in one-dimensional photonic crystals. Especially for the forward and backward incident light, the blueshift and dispersionless of the forward and backward cavity modes are designed respectively to realize the interesting omnidirectional nonreciprocal absorber. Our results show high (low) absorption about 0.99 (0.25) in an angle range of 20-75 degrees for the forward (backward) incident light at the wavelength of 367 nm. The nonreciprocal omnidirectional cavity mode not only facilitates the design of perfect unidirectional optical absorbers working in a wide-angle range, but also possesses significant applications for all-angle reflectors and filters.
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