Toward the generation of broadband optical vortices: extending the spectral range of a q-plate by polarization-selective filtering

Abstract

Optical vortex beams in the visible and nIR spectrum over a wide spectral region are generated by a single S-Waveplate polarization converter using polarization-selective filtering. A spectral coverage of 600 nm is demonstrated, with maximum efficiency at a wavelength of 530 nm. The broadband coverage is obtained using polarization filtering, which is applicable for any component based on geometric phase retardation. The efficiency of the filtering varies from 50% to 95% depending on the wavelength. This technique has a potential application in stimulated emission depletion (STED) microscopy and lithography.

Transmission of Orbital Angular Momentum and Cylindrical Vector Beams in a Large-Bandwidth Annular Core Photonic Crystal Fiber

“…We further note that, prior to our experimental investigation, we measured the laser light coupling efficiency into the AC-PCF for the Gaussian and the vector-vortex beams as 58% and 44%, respectively. Figure 4 (a,b,c) displays the intensity profiles of a vortex and a reference Gaussian beam as they are gradually superposed to create the single fork pattern expected for the interference of a L = +1 helically-phased OAM beam with a tilted reference beam of constant phase front [32,33]. Similarly, Figure 4 (d,e) shows a similar fork interference pattern created by the superposition of a reference Gaussian beam and the vortex beam output from the AC-PCF.…”

Multispectral Management of the Photon Orbital Angular Momentum

“…This solves previous optical state dispersion drawbacks associated with the global processing of the whole spectrum using "Bragg-Berry" optical elements [19]. Note that broadband optical vortex generation based on geometric phase has been reported using various approaches [20][21][22][23][24][25][26][27][28]; however, none of them enables spectral agility of the associated photon orbital angular momentum. Here, wavelength-dependent orbital angular momentum control is also achieved, as illustrated in Fig.…”

Vortex terahertz wave generation in air by femtosecond optical vortex pulses

“…In this position SH had central wavelength of 395 nm, FWHM pulse duration ∼50 fs and energy of 60 µJ in Gaussian state and 50 µJ in vortex state. Gaussian SH was converted to an optical vortex by a method described in, 27 which ensures more than octave spectral bandwidth of vortex generation. First SH was circularly polarized by a quarter wave plate (QWP) and converted to an optical vortex (OV) beam by an S-waveplate (RPC-405-06-557, Workshop of Photonics) (SWP).…”