RESUMEN
A novel nonparaxial scalar theory is presented to calculate the angular scattering that is due to interface roughnesses or bulk inhomogeneities in a high-quality optical coating. Based on the empirically modified Beckmann-Kirchhoff surface scatter model, this theory in surface scattering and bulk scattering predicts similar formulas for the angular scattered intensity, and at the same time provides new understanding and insight into multilayer scattering phenomena. It is worth noting that the derived expressions are in the same form as those given by the typical vector methods. Based on comparisons of the surface and bulk models with the corresponding typical models for several multilayer designs, the novel theory is demonstrated to be valid for multilayer coatings even with large incident and scattering angles.
RESUMEN
Transverse modes of light have been widely exploited in both classical and quantum optics in recent years. Among the devices to manipulate the transverse modes of light, a π/2 converter is a fundamental and important one that analogs to the quarter-wave plate in the polarization degree of freedom. While a π/2 converter is typically achieved by a pair of well-adjusted cylindrical lenses, it suffers from complexity in its installation and adjustment, which strongly limits its practical applications. In this paper an integrated design of a π/2 converter is reported. We compute the necessary parameters for manufacturing according to refractive theory of a cylindrical surface. Based on the change of refractive indices, we simulate the response of Gouy phase versus wavelengths. We also implement an experiment to verify the conversion between Laguerre-Gaussian modes and Hermite-Gaussian modes by using our compact π/2 converter to confirm its simple adjustment and reliable performance in practice.
RESUMEN
A novel first-order nonparaxial scalar theory for calculating the angular scattering that is caused by the interface roughness in an optical multilayer was proposed. As in the case that the interface roughness is moderate, the analytic expressions of angular-resolved scattering for a typical p-layer design were derived. Notably, these formulas are general because they do not depend on the prior restrictive hypothesis for the correlation degree of the various interfaces in a stack. In order to verify the theory, the formulas in the case of single-surface are presented and are exactly identical to those of the generalized Harvey-Shack theory. Also, their smooth-surface approximations are the same in form as those given by the typical first-order vector perturbation theories and are validated by numerically comparing with the typical vector theory for three representative multilayer design types with slightly rough interfaces. In addition, the usability of the novel theory in the case of moderate roughness is discussed by comparing this theory to the typical theories for optical coatings at different roughness levels.