Hybrid plasmonic coupling through multilayer optimum microcavity based quantum dots random laser

The development of random laser-based devices remains a key challenge due to their low efficiency. This study investigates the performance of multilayered random laser cavities encompassing silver nanoparticles and quantum dots as scatters and gain mediums respectively on silver film coated glass substrate. Polyvinyl alcohol as a spacer layer between gain and scatters enables the engineering of plasmon–exciton couplings; its thickness variation significantly influences the lasing threshold and slope efficiency under protective coating of Polydimethylsiloxane (PDMS). RL wavelength is red shifted from $\sim$ 636.5 nm to $\sim$ 645.4 nm under variation of spacer thickness from 0 nm to 137 nm attributed to variation in effective refractive index under the influence of plasmon–exciton interaction which enhanced radiative recombination as well. An optimal spacer thickness of 105 nm assisted in lowering the threshold value to 20 μJ/cm², underscoring improved energy confinement and lasing efficiency under hybrid plasmonic coupling. The power Fourier transform analysis of the random lasing spectra assisted the presented approach. These findings provide a compact strategy for developing wavelength-selective plasmon–exciton hybrid lasing systems in advanced photonic applications.