Slusar V. Properties of optical singular beam, which proguced by Laguerre-Gausian modes

Thesis for Candidate's Degree contains results of Laguerre-Gausian modes properties investigation. Beams with phase singularities, which obtained by superposition of Laguerre-Gausian modes investigated experimentally. New methodology and technique for orbital angular momentum investigation was elaborated. Experimental investigation of an optical vortex beam by means of a multiple-beam interference device is reported. Launching of an optical vortex beam into a prism-film coupler (leaky-wave planar waveguide) gives high angular resolution due to the resonant excitation of a propagating leaky mode. Observation of the dark line in the cross-section of the reflected beam visualizes a narrow range of equal incident angles within an optical beam with diffraction-limited divergence. The expectations from simple optical rays approach concerning the structure of an optical vortex are compared with the experimental results. A rotating spiral zone plate was used to implement and measure the rotational Doppler effect for plane-polarized optical beams with helical wave front (optical vortices). The frequency shift was analyzed in terms of energy exchange between the beams and moving optical elements. The initial beam carries photons with orbital angular momentum nћ to the plate; behind the spiral zone plate, the photon angular momentum in the Nth order equals (Nm + n) ћ. Hence, each photon acquires angular momentum Nmћ, so that a recoil torque is applied to the plate. In the course of rotation, the work against this torque changes the photon energy by ?? = Nmћ?. Hence it follows from the relation ?? = ћ?? that ?? = Nm?, irrespective of the optical vortex charge in the diffracted beam. New method of combined beam generation was proposed firstly. Space separation of LG01 and LG00 modes realized experimentally for combined beam with nonaxial optical vortex. This method gives possibility to separate Laguerre-Gausian modes with odd and even modal indexes, and can be used as principal for producing more complicated scheme ofmodes separation.