  Chiral light-matter interactions can enable polarization to control the
direction of light emission in a photonic device. Most realizations of chiral
light-matter interactions require external magnetic fields to break
time-reversal symmetry of the emitter. One way to eliminate this requirement is
to utilize strong spin-orbit coupling present in transition metal
dichalcogenides that exhibit a valley dependent polarized emission. Such
interactions were previously reported using plasmonic waveguides, but these
structures exhibit short propagation lengths due to loss. Chiral dielectric
structures exhibit much lower loss levels and could therefore solve this
problem. We demonstrate chiral light-matter interactions using spin-valley
states of transition metal dichalcogenide monolayers coupled to a dielectric
waveguide. We use a photonic crystal glide plane waveguide that exhibits chiral
modes with high field intensity, coupled to monolayer WSe2. We show that the
circularly polarized emission of the monolayer preferentially couples to one
direction of the waveguide, with a directionality as high as 0.35, limited by
the polarization purity of the bare monolayer emission. This system enables
on-chip directional control of light and could provide new ways to control spin
and valley degrees of freedom in a scalable photonic platform.
