A method of chromatic polarization imaging is presented for the online detection of colorless plastic contaminants from ginned cotton in an industrial setting. To understand the experimental results, we consider a realistic microscopic model, including the multiple scattering of anisotropic fibers and the light propagation in anisotropic slabs. A Monte Carlo code, based on the extended Jones matrix, is developed to simulate photon migration with polarization states, and phase information followed. Using simulations and experiments, we analyze the underlying mechanisms and evaluate the performance of this method with different layer thicknesses. Our approaches proposed in this Letter also have the potential to be applied in tissue imaging, remote sensing, and other scenarios.

The far-zone scattered spectral density of a light wave on the scattering from a collection of particles is investigated, and the relationship between the character of the collection and the distribution of the scattered spectral density is discussed. It is shown that both the number of particles and their locations in the collection play roles in the distribution of the far-zone scattered spectral density. This phenomenon may provide a potential method to reconstruct the structure character of a collection of particles from measurements of the far-zone scattered spectral density.

In order to improve the inversion precision of aerosol mass concentrations based on the particle group light scattering method, the concept that particles through a laser beam are equivalent to an aggregate is proposed. A fractal model for aerosol mass concentration using the signal amplitude distribution of aggregates is presented, and then the subsection calibration method is given. The experimental results show that the mass concentrations inversed by this model agree well with those measured by the norm-referenced instrument. The average relative errors of the two experiments are 5.6% and 6.0%, respectively, which are less than those obtained by the conventional inversion model.

The scattering properties of ZnO nanospheres with four different particle diameters of 10, 50, 100, and 200 nm suspended in water are investigated theoretical and experimentally in the spectral range of the entire visible range and part of the near-infrared region. The scattering properties of ZnO nanospheres suspended in water are described by employing three main parameters: the angular distribution of the scattering intensity I, the scattering extinction coefficient αscat, and the scattering cross section σscat. The results indicate that (i) at a certain wavelength, the angular distribution of the scattering intensity appears as an obviously forward-propagating feature, and the forward-scattering intensity is dominant gradually when the particle diameter increases from 10 to 200 nm, and (ii) the scattering extinction coefficient and cross section can be determined by using the measured transmittance changes of a pure water sample and a given ZnO sample; they all are shown to be dependent on the particle size and incident wavelength. The experimental results of four different scattering samples agree well with the theoretical predictions within the given wavelength range.

Calibration of the relationship between the scattering angle and the CCD pixel is a key part of achieving accurate measurements of rainbow refractometry. A novel self-calibrated global rainbow refractometry system based on illumination by two lasers of different wavelengths is proposed. The angular calibration and refractive index measurement of two wavelengths can be completed simultaneously without extra measurement devices. The numerical and experimental results show the feasibility and high precision of the self-calibration method, which enables the rainbow refractometry to be implemented in a more powerful and convenient way. The self-calibrated rainbow system is successfully applied to measure the refractive indices of ethanol-water solutions with volume concentrations of 10% to 60%.

The Brillouin gain properties in a double-clad As2Se3 photonic crystal fiber (PCF) are simulated based on the finite-element method (FEM). The results indicate that the Brillouin gain spectrum (BGS) of our proposed chalcogenide PCF exhibits a multipeaked behavior and has a high Brillouin gain coefficient. We also find that a larger size of inner cladding air holes will lead to a more pronounced second peak in the BGS. On the other hand, the size of the outer cladding has nearly no effect on the BGS behavior. Through these results, one can tailor the Stimulated Brillouin scattering effect in PCFs for a wide range of applications.

The polarization behavior of elastic scattering at 1473 nm is analyzed from a silicon microsphere on an optical fiber half-coupler. The 0.27 nm angular mode spacing of the resonances correlates well with the optical size of the silicon sphere. The spectral linewidths of the resonances are on the order of 10-3 nm, which corresponds to quality factors on the order of 106. The transverse magnetically polarized elastic scattering signal has higher resonance to modulation depth and background ratio than the transverse electrically polarized elastic scattering signal and is suitable for high-resolution optical filtering applications such as optical monitoring and sensing.