Tunable vector-vortex beam optical parametric oscillator

Abstract

Vector-vortex beams, having both phase and polarization singularities, are of great interest for a variety of applications. Generally, such beams are produced through systematic control of phase and polarization of the laser beam, typically external to the source. However, efforts have been made to generate vector-vortex beams directly from the laser source. Given the operation of the laser at discrete wavelengths, vector-vortices are generated with limited or no wavelength tunability. Here, we report an experimental scheme for the direct generation of vector-vortex beams. Exploiting the orbital angular momentum conservation and the broad wavelength versatility of an optical parametric oscillator, we systematically control the polarization of the resonant beam using a pair of intracavity quarter-wave plates to generate coherent vector-vortex beam tunable across 964–990 nm, with output states represented on the higher-order Poincaré sphere. The generic experimental scheme paves the way for new sources of structured beams in any wavelength range across the optical spectrum and in all time-scales from continuous-wave to ultrafast regime.

Phase Singularities to Polarization Singularities

“…e topology of VVB was also discussed [258,533]. Generation of vector beams using a double-wedge depolarizer [534], ring resonator [535], caustic-based approach [536], and parametric oscillator [537] was also demonstrated. Generation of broadband vector beams with tunable phase and polarization has been demonstrated in [538].…”

Compression and stretching of ring vortex in a bulk nonlinear medium

“…It is worth mentioning that the spatially varying strength of nonlinearity is confined within certain bounds, and the integration in V (r) converges, as indicated in Ref. [15]. Therefore, the expressions for V (r) and γ(r) impose certain conditions: ρ must not change sign and exhibit behavior as r −ϖ with ϖ ≥ 3 −1 as r approaches zero, while ρ diverges as r tends to infinity.…”

“…In pursuit of these applications, numerous remarkable technologies have been proposed to generate vector vortex beams; however, the creation of novel vector vortex beams remains a significant challenge. [15][16][17][18] Despite the availability of numerous numerical investigations, the analytical analysis concerning the formation of vector vortex solitons remains relatively limited.…”

Superposition of vortex beams generated by polarization conversion in uniaxial crystals

“…Due to the remarkable characteristics of VVBs and HVBs but also to their considerable applicability potential, plenty of generation techniques has been proposed. Some of them regard the VVBs generation by direct emission of laser beams with the desired optical vortex phase inside a laser cavity 9 – 11 . Despite the advantages of these techniques, like low cost, high power, and high efficiency, the systems could be deemed rigid in terms of the assortment of the generated VVBs.…”