Robust excitation and Raman conversion of guided vortices in chiral gas-filled photonic crystal fiber

Abstract

The unique ring-shaped intensity patterns and helical phase fronts of optical vortices make them useful in many applications. Here we report for the first time efficient Raman frequency conversion between vortex modes in twisted hydrogen-filled single-ring hollow core photonic crystal fiber (SR-PCF). High fidelity transmission of optical vortices in untwisted SR-PCF becomes more and more difficult as the orbital angular momentum (OAM) order increases, due to scattering at structural imperfections in the fiber microstructure. In helically twisted SR-PCF, however, the degeneracy between left- and right-handed versions of the same mode is lifted, with the result that they are topologically protected from such scattering. With launch efficiencies of ~75%, a high damage threshold and broadband guidance, these fibers are ideal for performing nonlinear experiments that require the polarization state and azimuthal order of the interacting modes to be preserved over long distances. Vortex coherence waves (VCW) of internal molecular motion, carrying angular momentum, are excited in the gas, permitting the polarization and orbital angular momentum of the Raman bands to be tailored, even in spectral regions where conventional solid-core waveguides are opaque or susceptible to optical damage.

References in corpus (10)

• Entanglement of Orbital Angular Momentum States of Photons
• Light with a self-torque: extreme-ultraviolet beams with time-varying orbital angular momentum
• Conservation of orbital angular momentum in air core optical fibers
• Discrete-symmetry vortices as angular Bloch modes
• Efficient spectroscopy of exoplanets at small angular separations with vortex fiber nulling
• Broadband-tunable LP${}_{01}$ mode frequency shifting by Raman coherence waves in H${}_2$-filled hollow-core PCF
• Coherent transfer of optical orbital angular momentum in multi-order Raman sideband generation
• Optical Angular Momentum Manipulations in a Four Wave Mixing Process
• Cascaded generation of multiply charged optical vortices and spatiotemporal helical beams in a Raman medium
• Polarization-Tailored Raman Frequency Conversion in Chiral Gas-Filled Hollow Core Photonic Crystal Fibers

Cited by in corpus (1)

• Stimulated Raman Scattering and Molecular Modulation in Anti-resonant Hollow-core Fibres