Modal gain enhancement of perovskite nanosheets by a patterned waveguide via spectral-length gain analysis

Abstract We have studied optical modal gain in two-dimensional perovskite nanostructures in terms of gain saturation and mode confinement, where CsPbBr3 nanosheets of large lateral size (80 ∼ 300 nm) and thin thickness (5 ∼ 8 nm) were stacked in a patterned waveguide of polyurethane-acrylate. Concerned with the uncertainties and pitfalls in retrieving gain coefficient from the variable stripe length method, we have obtained a gain contour g(ℏω, x), whereby gain saturation was analyzed in terms of both spectrum energy (ℏω) and stripe length (x). For increasing excitation and temperature, an average gain was also obtained from g(ℏω, x), where the two dimensional excitons and the localized states are involved. We found the waveguide enhances both modal gain and thermal stability due to the increased mode confinement and heat conduction.