Miniaturized coherent light sources on the nanoscale
are highly
desired for on-chip photonics integration. However, when approaching
the diffraction limit, the sub-wavelength-scale all-dielectric lasers
are difficult to realize due to the trade-off between lasing performance
and physical size. Especially for a thin-film laser, usually an externally
complex cavity is required to provide the necessary optical feedback.
Herein, we successfully shrink the MAPbBr3 perovskite thin-film
laser to sub-wavelength scale (300 nm) with simplified cavity design
using only an ultraviolet glue layer and a quartz glass. The morphology
quality and the gain properties of the film are enhanced by introducing
ionic liquid. Consequently, the stable and low-threshold single-mode
laser with a highly linear polarization degree of 78.6% and a narrow
line width of 0.35 nm is achieved under two-photon excitation. The
excellent single-mode laser with sub-wavelength scale and ultrasimplified
structure could provide a facile and versatile platform for future
integrated optoelectronic devices