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Spectral performance of a zero-order liquid-crystal polymer commercial q-plate for the generation of vector beams at different wavelengths


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Title:
Spectral performance of a zero-order liquid-crystal polymer commercial q-plate for the generation of vector beams at different wavelengths
Authors:
Sánchez López, María del Mar
Abella, Isaiah
Puerto García, Daniel
Davis, Jeffrey A.
Moreno Soriano, Ignacio
Editor:
Elsevier
Department:
Departamentos de la UMH::Física Aplicada
Issue Date:
2018
URI:
https://hdl.handle.net/11000/31236
Abstract:
Liquid-crystal polymer q-plates are commercial devices for generating vector beams at the design wavelength where the device exhibits half-wave (HW) retardance. Since they are not voltage addressable, the operational wavelength remains fixed. In this work we perform a broadband spectral characterization of the q-plate retardance as a function of wavelength, /(k), and identify the wavelengths with retardance values relevant for vector beam generation (p, p/2, and 3p/2). The wavelength is then used as a tuning parameter to change the device performance from a HW q-plate to a positive-QW or a negative-QW q-plate. These performances are analyzed using the Jones matrix formalism. We present a simple procedure to derive the polarization distribution of the vector beams expected at these QW wavelengths, as a superposition of the input polarization state and the output state of a HW q-plate. Experimental results using the red and blue lines of an Ar-Kr laser and an IR laser diode of 980 nm confirm the theoretical predictions. We show that for input linearly polarized light of 980 nm and 488 nm the device generates hybrid vector beams (where the ellipticity varies with the azimuthal angle), while for 647 nm pure radial vector beams with constant ellipticity are obtained. These results could extend the use of commercial q-plates for multicolour vector beam applications.
Keywords/Subjects:
q-plates
vector beams
spectral retarders
orbital angular momentum
space-variant phase retarders
Knowledge area:
CDU: Ciencias puras y naturales: Física
Type of document:
application/pdf
Access rights:
info:eu-repo/semantics/openAccess
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
DOI:
https://doi.org/10.1016/j.optlastec.2018.04.008
Appears in Collections:
Instituto de Bioingeniería



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