Rhodamine 6G laser dye with dandelion seed pappus biogenic scatterers for low-threshold random lasing and speckle-free imaging

Dandelion seed pappus as a green scattering medium for low-threshold random lasers and speckle-free imaging. • Rhodamine 6G laser dye was combined with dandelion seed pappus biowaste to construct a green, low-threshold random laser. • The biogenic scattering network delivers an ultralow lasing threshold of 5.81 μJ/mm 2 with stable coherent emission. • Replica symmetry breaking confirms the phase transition from ASE to stable random lasing in dye-biomass hybrid system. • The laser dye-based random laser enables 301% SNR enhancement and 86% speckle reduction for high-fidelity imaging. Developing efficient laser dyes with sustainable biogenic scatterers is highly desirable for green optoelectronics. This work reports a high-performance random laser (RL) system using Rhodamine 6G as laser dye and dandelion seed pappus (DSP) biowaste as a natural scattering medium. By integrating DSP fibers with Rhodamine 6G as the gain media and polyvinylpyrrolidone dispersants in an ethanol solution, we constructed a three-dimensional disordered scattering network. Systematic optimization revealed a remarkably low lasing threshold of 5.81 μJ/mm 2 at a DSP concentration of 2 mg/mL. This superior performance is attributed to the naturally evolved, irregular flake-like microstructures of DSP, which maximize multiple scattering efficiency while minimizing parasitic optical loss. The underlying physics was elucidated through power fourier transform (PFT) analysis to identify the effective cavity length— L C  = 191.20 μm, while replica symmetry breaking (RSB) validated the transition to stable, coherent random lasing with high spectral integrity over 1500 pulses. Leveraging its intrinsically low spatial coherence, the DSP-based RL was deployed for high-fidelity speckle-free imaging, yielding a 301% enhancement in signal-to-noise ratio (SNR) and an 86% reduction in speckle contrast compared to conventional coherent lasers. The practical utility was successfully demonstrated across resolution targets, biological specimens, and microelectronic architectures. This work provides a compelling strategy for converting seasonal plant waste into advanced functional materials, offering a robust, green roadmap for next-generation biomedical imaging and optical inspection systems.