Femtosecond laser nanostructuring for high-topological charge vortex tweezers with continuously tunable orbital angular momentum

Femtosecond laser nanostructuring for high-topological charge vortex tweezers with continuously tunable orbital angular momentum

It is well known that the light carries linear and angular momentum that can be transferred to the irradiated objects. Angular momentum of the beam is comprised of spin angular momentum (SAM) and orbital angular momentum (OAM). SAM is associated to the beam's polarization and is always intrinsic. OAM comes from the azimuthal phase variations of the beam and can be both extrinsic and intrinsic. The beam with helical phase phi = l.Phi, where phi is phase, Phi is polar angle and l is positive or negative integer number, possesses well-defined OAM with l.h [1]. Such beams are often referred to as optical vortices and are exploited in optical tweezer experiments enabling the rotation of trapped particles. Changing the wavefront's helicity, also the geometry of the beam is changed. The higher is |l|, the larger is the diameter of the beam. In order to change the total angular momentum of the beam, either the shape of the beam or the photon density has to be changed. As a result, the experiments which require fixed beam size and intensity are limited to fixed OAM. Recently, we implemented optical tweezers with tunable angular momentum, there OAM could be changed from -1 to 1 by controlling ellipticity of the incident laser beam. Here we extend this technology and demonstrate the generation of optical vortices of high topological charge up to 100 (Fig. 1(a)-(i)) using femtosecond laser written polarization converters (the S-waveplate) [2].

Drevinskas, Rokas

23f858b5-8750-4113-ba11-49cfefc3dbb7

Gecevičius, Mindaugas

271576ee-dd9d-40b3-ab2f-19686b91dc64

Beresna, Martynas

a6dc062e-93c6-46a5-aeb3-8de332cdec7b

Kazansky, Peter G.

a5d123ec-8ea8-408c-8963-4a6d921fd76c

2015

Drevinskas, Rokas

23f858b5-8750-4113-ba11-49cfefc3dbb7

Gecevičius, Mindaugas

271576ee-dd9d-40b3-ab2f-19686b91dc64

Beresna, Martynas

a6dc062e-93c6-46a5-aeb3-8de332cdec7b

Kazansky, Peter G.

a5d123ec-8ea8-408c-8963-4a6d921fd76c

Drevinskas, Rokas, Gecevičius, Mindaugas, Beresna, Martynas and Kazansky, Peter G.
(2015)
Femtosecond laser nanostructuring for high-topological charge vortex tweezers with continuously tunable orbital angular momentum.
*
The European Conference on Lasers and Electro-Optics, Munich.
20 - 24 Jun 2015.
*

Record type:
Conference or Workshop Item
(Paper)

## Abstract

It is well known that the light carries linear and angular momentum that can be transferred to the irradiated objects. Angular momentum of the beam is comprised of spin angular momentum (SAM) and orbital angular momentum (OAM). SAM is associated to the beam's polarization and is always intrinsic. OAM comes from the azimuthal phase variations of the beam and can be both extrinsic and intrinsic. The beam with helical phase phi = l.Phi, where phi is phase, Phi is polar angle and l is positive or negative integer number, possesses well-defined OAM with l.h [1]. Such beams are often referred to as optical vortices and are exploited in optical tweezer experiments enabling the rotation of trapped particles. Changing the wavefront's helicity, also the geometry of the beam is changed. The higher is |l|, the larger is the diameter of the beam. In order to change the total angular momentum of the beam, either the shape of the beam or the photon density has to be changed. As a result, the experiments which require fixed beam size and intensity are limited to fixed OAM. Recently, we implemented optical tweezers with tunable angular momentum, there OAM could be changed from -1 to 1 by controlling ellipticity of the incident laser beam. Here we extend this technology and demonstrate the generation of optical vortices of high topological charge up to 100 (Fig. 1(a)-(i)) using femtosecond laser written polarization converters (the S-waveplate) [2].

## More information

Published date: 2015

Additional Information:
ECBO_2_3

Venue - Dates:
The European Conference on Lasers and Electro-Optics, Munich, 2015-06-20 - 2015-06-24

Organisations:
Optoelectronics Research Centre

## Identifiers

Local EPrints ID: 384262

URI: http://eprints.soton.ac.uk/id/eprint/384262

PURE UUID: 1e59ca1c-2d37-43ab-9db9-839b02c966f0

## Catalogue record

Date deposited: 26 Nov 2015 14:36

Last modified: 13 Jul 2020 16:38

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## Contributors

Author:
Rokas Drevinskas

Author:
Mindaugas Gecevičius

## University divisions

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