Efficient multilayer near-infrared micro-bottle laser pumped by a 532 nm nanosecond laser

This paper explores the development and optimization of organic near-infrared micro-cavity lasers for biophotonic applications. Four micro-bottle laser configurations inclouding single-layer, two-layer, and three-layer structures were designed and fabricated using Nile-Blue (NB) and Rhodamine B (RhB) laser dyes doped in SU-8 polymer as laser-active materials. While NB achieves lasing near 750 nm, its absorption of common pump sources such as Nd: YAG lasers at 532 nm is limited. Therefore, Forster resonance energy transfer (FRET) between RhB and NB was employed to enhance NB's lasing efficiency under 532 nm excitation. Experimental and simulation results demonstrate that multilayer designs, particularly the three-layer configuration, outperform others, achieving higher emission intensity, improved stability, and reduced lasing thresholds. The inclusion of RhB optimizes pump absorption and enables efficient energy transfer, facilitating stable Near-IR lasing at 720-750 nm. These findings highlight the potential of multilayer micro-cavity lasers for compact, efficient, and stable organic laser systems in biophotonic and sensing applications.