No abstract

No abstract

Future optical technologies are basically depending on and employing different types of optical waveguides. The fabrication of waveguides with different properties represents an expanding direction in both the industrial and scientific fields. In the current paper, we focus on studying the polymeric planar waveguides fabricated by the method of UV–excimer–laser lithography. We propose a general technique based on the WKB approximation and digital holographic interferometry to characterize slab waveguides with arbitrary refractive index profile. The necessary theoretical model is derived and the characterization method given in detail. Two samples are fabricated from polymethylmethacrylate (PMMA) polymeric material using different parameters for the used UV-laser. Then a phase-shifting digital holographic technique with the help of a Mach–Zehnder-like interferometer, is used to characterize the samples and measure their modified refractive index profiles. The resulting profiles are then fed to the proposed theoretical model and a full TE mode analysis is obtained. These results prove the ability of the proposed technique to analyze planar waveguides having any complicated refractive index profile.

Studying the polarization of paraxial beams propagating through uniaxial anisotropic crystals at an arbitrary angle is a powerful feature to extend the range of utilization of these crystals. In this paper, we derive a general theoretical model, based on the existing theory, to describe the transformations of polarization state in cases of arbitrary beam propagation. Stokes parameters are employed for the determination of polarization state of the light beam. The derived model is applied to a linearly polarized quasi-Gaussian beam propagating through rutile crystal. The dependence of the polarization state of the beam on many parameters such as beam waist, angle of propagation, and thickness of the crystal is investigated. The variation of each of these parameters leads to an extensive and interesting change of the polarization state. Moreover, the results are employed to observe the variations of the spin angular momentum as a function of the above-mentioned parameters. Furthermore, we report on an interesting result regarding the longitudinal component of the propagating field, where we noticed the existence of clearly non negligible values of this component for certain propagation parameters. The results of the current work are promising and can be utilized to obtain the best functioning of the output beam depending on its shape and polarization. In addition, they are promising for other future applications such as designing polarization-based devices which are useful in many fields.