Lasing in dye-infiltrated nanoporous anodic alumina membranes

Laser emission is obtained from a slab of nanoporous anodic alumina on an aluminum sheet, infiltrated by rhodamine 6G dye in methanol and pumped by 532 nm, 700 ps laser pulses. The nanostructured surface maintains a continuous flow of the dye solution by wetting and evaporation of methanol. Emission along the stripe of the pump light was measured in a 30 μm-thick nanoporous slab to have sharp peaks with line widths < 1.5 nm and spacing of about 2 nm. The output emission is polarized predominantly parallel to the slab and random lasing effects due to scattering in the nanoporous alumina are minimal. We achieve stable lasing in a 1.8 μm-thick nanoporous membrane by depositing a thin layer of gold on the top facet of the membrane. The improved reflectivity from the gold-coated surface further assists the guiding of emitted light along the lasing stripe. The minuscule size of our dye-infiltrated nanoporous membrane resembling microchip lasers is potentially applicable as micro-fluidic lasers for lab-on-a-chip devices.