Controlling the contribution of the electric field components to the focus of a high-aperture lens using binary phase structures

Abstract

We show that the contribution of the electric field components into the focal region can be controlled using binary phase structures. We discuss differently polarized incident waves, for each case suggesting easily implemented binary phase distributions that ensure a maximum contribution of a definite electric field component on the optical axis. A decrease in the size of the central focal spot produced by a high numerical aperture (NA) focusing system comes as the result of the spatial redistribution of the contribution of different electric field components into the focal region. Using a polarization conversion matrix of a high NA lens and the numerical simulation of the focusing system in Debye's approximation, we demonstrate benefits of using asymmetric to polar angle ϕ binary phase distributions (such as arg[cos ϕ] or arg[sin 2ϕ]) for generating a subwavelength focal spot in separate electric field components. Additional binary structure variations with respect to the azimuthal angle also make possible controlling the longitudinal distribution of light. In particular, the contribution of the transverse components in the focal plane can be reduced by the use of a simple axicon-like structure that serves to enhance the NA of the lens central part, redirecting the energy from focal plane. As compared with the superimposition of a narrow annular aperture, this approach is more energy efficient, and as compared with the Toraldo filters, it is easier to control when applied to three-dimensional focal shaping.

Contribution Samara scientists in the development of the journal "Computer Optics"

“…This permitted a substantial improvement of the journal indicators calculated in the SCOPUS database (Figures 1-4 [107,34,33,48], in 2010 [108,109,27], in 2011 [54][55] in 2012 [49,110] in 2013 [62,111,112], in 2014 [113-115, 65, 50, 66] and in 2015 [68,39,116,117]) were published by Samara scientists.…”

Study of polarization sensitivity OF near-field microscope using a binary phase plate

“…В работе [16] было показано, что фокальная картина и, соответственно, вклад продольной компоненты в цен-тральную часть фокальной области зависит от взаимного расположения оси поляризации и линии фазового скачка пластины. При их ортогональном положении обеспечи-вается максимальное содержание продольной компонен-ты в фокусе, а при совпадении осей -минимальное.…”

Synthesis of highly focused fields with circular polarization at any transverse plane

“…The propagation of electromagnetic field distributions generated at the focal region has been extensively investigated in the last years [1][2][3][4][5][6][7][8]. Non-paraxial fields have demonstrated very useful in many fields for instance in high-resolution microscopy, particle trapping, high-density recording, tomography, electron acceleration, nonlinear optics, and optical tweezers [9].…”