STI Virtual Seminar Today Tuesday 13 September 2022 at 3 pm (Rome time)

[STI Secretariat]

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STI seminar
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You are most cordially invited to a virtual seminar organized by the 
ICTP Science Technology and Innovation Unit (STI Unit)

** * * TODAY - Tuesday, 13 September 2022 at 15:00 (Rome/CEST time) *** * **

Register in advance for this seminar:

https://zoom.us/meeting/register/tJclcO2trTwoH9ea_iBUI_VYtkAHYEq-dNWV
/
/After registering, you will receive a confirmation email containing 
information about joining the seminar.


Speaker: *Saifollah RASOULI, *Institute for Advanced Studies in Basic 
Sciences (IASBS), Zanjan, Iran

Title:** *Diffraction-based methods for characterizing and 
multiplication of optical vortices and generation of multiple particles 
trapping*

_Abstract_

In this talk, a comprehensive theory for the diffraction of vortex beams 
from structured apertures especially from one- and two-dimensional (2D) 
periodic and quasi-periodic structures is introduced, and efficient 
robust and reliable diffraction-based methods for characterization and 
multiplication of the optical vortices are proposed. It is shown that in 
the diffraction of a vortex beam from 2D periodic structures having 
sinusoidal or Ronchi profiles, only for the odd values of the 
topological charge (TC) of the incident beam, the vortex beam is 
multiplied over an array at the Talbot planes of the structure, in which 
the TCs of all of the generated vortex beams are equal to one. It is 
also shown that when the opening number of the 2D binary grating is less 
than 1/2, for the both odd and even values of the TC of the incident 
beam, at the distinct Talbot planes, arrays of vortex beams having the 
same TC of the incident beam are generated. For this grating the former 
behavior is also observed but at different propagation distances. In 
addition, grating-based diffraction methods for generation of structured 
beams are introduced. The use of Fraunhofer diffraction patterns of 
almost-periodic structures for 3D multiple particles trapping is also 
proposed. Some experimentally multiple particles trapping and 
manipulation using the introduced methods are presented.

-- 
Nicoletta Ivanissevich (Ms.)
Secretariat,
STI - Science, Technology and Innovation Unit
The Abdus Salam International Centre for Theoretical Physics
Strada Costiera, 11
I-34151 Trieste
Italy

Phone: +39-040-2240.383
STI Webpage:https://www.ictp.it/research/sti.aspx
Email:sti at ictp.it

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