Properties of Random Lasers in a hollow core photonic crystal fiber

We investigate the properties of random lasers based on light guiding and scattering in a hollow core photonic crystal fiber. We develop air-filled and filled cladding for different fiber core diameters of photonic crystal fibers. The fiber cores are filled with various concentrations of alumina nanoparticles (similar to 50 nm) and Rhodamine 6G in ethylene glycol solution. The effects of light guiding and scattering were studied in terms of filled and air-filled cladding, different fiber core diameters and scattering regimes. Fiber with air-filled cladding provides guiding to the sample leading to random lasing, whereas the sample without scattering does not produce any narrow emission spectra. Less scattering is needed for random lasers in a fiber because too much scattering may hinder guiding in the fiber core leading to high lasing threshold. Both guiding and scattering are needed in random lasers in a fiber as the absence of one of these light phenomena results in broad emission spectra with no lasing threshold. The experimental results are supported with the numerical modeling. We observe that random lasers perform better in the weakly scattering regime than the diffusive regime, which is well predicted by the modeling.