Research Projects

The development of light sources with narrow spectral bandwidth, high brightness, and low spatial coherence is critical for high-resolution optical imaging and free-space optical communication. Traditional lasers, while intense and spectrally narrow, suffer from high spatial coherence, producing speckle noise that degrades imaging. Random lasers, which lack a conventional cavity and rely on multiple scattering for feedback, provide an alternative with low spatial coherence and good directionality. Polymer Optical Fibers (POFs), with their flexibility and tunability, are ideal hosts for integrating random laser systems. The central hypothesis of this proposal is that directional random lasers based on dye-doped POFs embedded with tailored scattering nanostructures can deliver narrowband, low-threshold emission with reduced speckle—suitable for robust imaging in complex environments. Furthermore, we hypothesize that plasmonic dielectric and biological scatterers can modulate lasing behavior to enhance performance and enable imaging capabilities. The scientific objectives are to: 1. Develop flexible, low-threshold random lasers using dye-doped hollow POFs. 2. Investigate the effect of scattering media (ZnO, dielectric, plasmonic, and biological nanostructures) on lasing threshold, mode structure, and emission stability. 3. Demonstrate speckle-free imaging using the optimized random laser system. 4. Understand nanoparticle-assisted light localization in cylindrical microcavities. The main experiments include: • Fabrication of dye-doped POFs configured as hollow waveguides. • Integration of scattering media (ZnO, TiO₂, gold/silver nanoparticles) via coating or solution filling. • Characterization of lasing spectra, threshold behavior, and coherence properties using photodetectors and spectrum analyzers. • Incorporation of biological scatterers (DNA-lipid complexes, tissue samples) to evaluate bio-compatibility and environmental response. • Speckle-free imaging tests using CCD cameras to validate real-world applicability. A unique aspect of this project is the integration of nanostructures synthesized via solvent-assisted techniques, offering high scattering efficiency and spectral tunability. The dual use of synthetic and biological scatterers allows a broader exploration of random lasing phenomena and their potential applications. If successful, this work will significantly advance the fundamental understanding of random lasing in flexible fiber platforms, especially regarding directional emission, threshold control, and mode tuning. From an application perspective, the project will contribute to the development of compact, speckle-free imaging sources, tunable photonic devices, and bio-compatible optical diagnostics. This research is novel in the Indian context and builds on the prior expertise of the team in polymer fiber lasers and nanophotonics.