  In addition to a plethora of emergent phenomena, the spatial topology of
optical vortices enables an array of applications spanning communications to
quantum photonics. Nonlinear optics is essential in this context, providing
access to an infinitely large set of quantum states associated with the orbital
angular momentum of light. Nevertheless, the realization of such processes have
failed to keep pace with the ever-growing need to shrink the fundamental
length-scale of photonic technologies to the nanometer regime6. Here, we push
the boundaries of vortex nonlinear optics to the ultimate limits of material
dimensionality. By exploiting second and third-order frequency-mixing processes
in semiconducting monolayers, we demonstrate the independent manipulation of
the wavelength, orbital angular momentum, and spatial distribution of vortex
light-fields. Due to the atomically-thin nature of the host quantum material,
this control spans a broad spectral bandwidth in a highly-integrable platform,
unconstrained by the traditional limits of bulk nonlinear optical materials.
Our work heralds a new avenue for ultra-compact and scalable hybrid
nanotechnologies empowered by twisted nonlinear light-matter interactions in
van der Waals quantum nanomaterials.
