Self-organized optofluidic locking enables stable single-frequency lasing in dynamic liquid media

Liquid-state lasers are promising wavelength-agile, reconfigurable coherent light sources, but fluid gain media introduce Brownian motion, thermal transport, and refractive-index fluctuations that destabilize single-frequency emission. Here, we demonstrate that nonequilibrium fluid fluctuations can instead be harnessed to stabilize lasing through optofluidic locking. In anisotropic colloidal nanoplatelets (CNPs), a weak auxiliary continuous-wave optical field induces collective particle migration, reorientation, and accumulation via coupled optical forces and convective flow. The resulting self-organized gain landscape suppresses cavity fluctuations, improves output stability by nearly three orders of magnitude, and reduces the lasing threshold by over 75%. Integrated with high-gain CdSe/CdSeS/CdZnS core/graded-crown/graded-shell nanoplatelets and a Littman-like external cavity, this mechanism enables stable single-frequency lasing with a side-mode suppression ratio above 31 dB, a 0.051 nm linewidth, and 170-nm single-mode tunability across engineered CNP gain media. We further demonstrate applications in WS₂ photoluminescence pumping and wavelength-tunable topological vertical-cavity lasing.