Physical optics

About: Physical optics is a research topic. Over the lifetime, 5342 publications have been published within this topic receiving 101388 citations. The topic is also known as: wave optics.

Backward Scattering of Electrically Large Standard Objects Illuminated by OAM Beams

Abstract: To evaluate the interaction between the orbital angular momentum (OAM) beams and the electrically large standard objects, the backward scattering characteristics of the perfect electrical conductor (PEC) sphere and PEC cone are studied. First, the incident vortex electromagnetic field carrying OAM is generated by Hertizian dipole arrays. Subsequently, the backward-scattered field is calculated by the physical optics algorithm. The phase profiles and OAM spectra are analyzed in detail, which indicates that the scattered field for axial symmetric objects still keeps the main characters of the vortex field due to the angular momentum conservation. Finally, the radar cross section for PEC sphere and cone are calculated, respectively. The backward scattering features show significant differences when OAM beams change their topological charges. Consequently, given a specific propagation direction, compared to plane waves, more information will be offered by the OAM beams for object detection and recognition.

Millimeter wave scattering model for a leaf

Abstract: At millimeter wave frequencies a typical leaf is a significant fraction of a wavelength in thickness, and its nonuniform dielectric profile now affects the scattering. To provide a simple and efficient method for predicting the scattering, two types of physical optics approximations are examined. The first approximates the volume polarization current by the current which would exist in an infinite dielectric slab with the same profile, while the second (and simpler) one employs the surface current which, on the infinite slab, produces the known reflected field. It is shown that the first method is superior, and, provided the actual dielectric profile is used, it predicts the scattered field to an accuracy which is adequate for most practical purposes.

Physical optics models for the backscatter response of road-surface faults and roadside pebbles at millimeter-wave frequencies

Abstract: Theoretical models, based on the physical optics (PO) approximation, are presented to predict the backscatter response of road-surface faults and roadside pebbles. Two types of surface faults are considered, cracks and potholes. By applying the PO model, the backscattering coefficients of a road-surface crack are approximated by the radar cross section (RCS) per unit length of a lossy dielectric cylinder. For a road-surface pothole with a simple geometry, its RCS is estimated by the coherent sum of the backscattered fields from the pothole edges with significant backscatterers. The backscatter response of roadside pebbles is a combination of the surface scattering from surface roughness and the volume scattering from a layer of rock particles. The surface scattering is depicted by the integral equation method, a simplified second-order iterative physical optics approximation. The hybrid scattering model based on the theory of vector radiative transfer is employed to predict the volume scattering. The validity of the theoretical models is examined by comparing the simulation results with experimental data from the University of Michigan, where backscatter measurements at W-band frequencies were conducted on road-surface faults and roadside pebbles at near grazing incidence angles (74/spl deg/-88/spl deg/) (Sarabandi, K. et al., ibid., vol.45, p.1679-88, 1997; Li and Sarabandi, ibid., vol.47, p.851-61, 1999).

Pump-probe reflective polarization-sensitive nonlinear optics

Abstract: We report on the phenomenological theory of frequency degenerate pump–probe polarization-sensitive wave interactions at the boundary with a nonlinear medium. We consider media with local and nonlocal optical responses. The general analytical solutions for polarization-plane azimuth rotation and ellipticity of the transmitted and reflected probe waves are obtained. It is found that the pump-intensity-dependent change of the polarization state of transmitted and reflected probe waves has coherent and incoherent contributions. Nonlinear polarization phenomena of the specular inverse Faraday effect, the specular optical Kerr effect, the specular nonlinear anisotropic effect, specular nonlinear optical activity, and specular nonlinear nonlocal birefringence are discussed.