  Monolayers of transition metal dichalcogenides (TMDCs) have emerged as new
optoelectronic materials in the two dimensional (2D) limit, exhibiting rich
spin-valley interplays, tunable excitonic effects, and strong light-matter
interactions. An essential yet undeveloped ingredient for many photonic
applications is the manipulation of its light emission. Here we demonstrate the
control of excitonic light emission from monolayer tungsten diselenide (WSe2)
in an integrated photonic structure, achieved by transferring one monolayer
onto a photonic crystal (PhC) with a cavity. In addition to the observation of
greatly enhanced (~60 times) photoluminescence of WSe2 and an effectively
coupled cavity-mode emission, we are able to redistribute the emitted photons
both polarly and azimuthally in the far field through designing PhC structures,
as revealed by momentum-resolved microscopy. A 2D optical antenna is thus
constructed. Our work suggests a new way of manipulating photons in hybrid 2D
photonics, important for future energy efficient optoelectronics and 2D
nano-lasers.
