  Exciton-polaritons are unique quasiparticles with hybrid properties of an
exciton and a photon, opening ways to realize ultrafast strongly nonlinear
systems and inversion-free lasers based on Bose-Einstein polariton
condensation. However, the real-world applications of the polariton systems are
still limited due to the temperature operation and costly fabrication
techniques for both exciton materials and photon cavities. 2D perovskites
represent one of the most prospective platforms for the realization of strong
light-matter coupling since they possess room-temperature exciton states with
large oscillator strength and can simultaneously provide planar photon cavities
with high field localization due to the huge refractive index of the material.
In this work, we demonstrate for the first time the mechanical scanning probe
lithography method for the realization of low-cost room-temperature
exciton-polariton systems based on the 2D perovskite (PEA)$_2$PbI$_4$ with
exciton binding energy exceeding 200 meV. Precisely controlling the lithography
parameters, we broadly adjust the exciton-polariton dispersion and radiative
losses of polaritonic modes in the range of 0.1 to 0.2 of total optical losses.
Our findings represent a versatile approach to the fabrication of planar
high-quality perovskite-based photonic cavities supporting the strong
light-matter coupling regime for the development of on-chip all-optical active
and nonlinear polaritonic devices.
