טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGorodetski Yuri
SubjectOptical Properties of Polarization-Depended Geometric
Phase Elements with Partially Polarized Light
DepartmentDepartment of Mechanical Engineering
Supervisor Professor Erez Hasman


Abstract

The behavior of geometric phase elements illuminated with partially polarized monochromatic beams is investigated both theoretically and experimentally. The discussed element is composed of wave plates with constant retardation and a space-variant orientation angle. We found that a beam emerging from such an element comprises three polarization orders; the first is in the original polarization state, and the second and the third are right-and left-handed circularly polarized states with conjugate geometric phase modification. This phase equals twice the orientation angle of the space-variant wave plate comprising the element. Apart from the three polarization orders, the emerging beam coherence polarization matrix includes a "vectorial interference matrix" which contains information concerning the correlation between the two orthogonal, circularly polarized portions of the incident beam. We measure this correlation by a simple interference experiment. In addition, we found that the equivalent mutual intensity of the emerging beam is modulated according to the geometric phase induced by the element. Other interesting phenomena concerning propagation will be discussed theoretically and demonstrated experimentally.


The experiments made use of a spherical p-retardation geometric phase element that was realized by use of a space-variant subwavelength grating illuminated with CO2 laser radiation of 10.6mm wavelength. A method for polarimetric measurement using such grating with linear geometric phase and p/2 - retardation is also presented. The polarization state is retrieved by measuring the far-field intensity of a beam emerging from the grating followed by a polarizer. The analysis for a partially polarized, quasi-monochromatic beam is performed using the beam coherence polarization matrix along with the extended van Cittert-Zernike theorem. We experimentally demonstrate polarization measurements of both fully and partially polarized light.