  Subwavelength periodic confinement can collectively and selectively enhance
local light intensity and enable control over the photo-induced phase
transformations at the nanometer scale. Standard nanofabrication process can
result in geometrical and compositional inhomogeneities in optical phase change
materials, especially chalcogenides, as those materials exhibit poor chemical
and thermal stability. Here we demonstrate the self-assembled planar
chalcogenide nanostructured array with resonance enhanced light emission to
create an all-dielectric optical metasurface, by taking advantage of the fluid
properties associated with solution processed films. A patterned silicon
membrane serves as a template for shaping the chalcogenide metasurface
structure. Solution-processed arsenic sulfide metasurface structures are
self-assembled in the suspended 250 nm silicon membrane templates. The periodic
nanostructure dramatically manifests the local light-matter interaction such as
absorption of incident photons, Raman emission, and photoluminescence. Also,
the thermal distribution is modified by the boundaries and thus the
photo-thermal crystallization process, leading to the formation of anisotropic
nano-emitters within the field enhancement area. This hybrid structure shows
wavelength selective anisotropic photoluminescence, which is a characteristic
behavior of the collective response of the resonant guided modes in a periodic
nanostructure. The resonance enhanced Purcell effect could manifest the quantum
efficiency of localized light emission.
