In many natural and industrial environments, small droplets are irradiated with visible and infrared light, affecting how they evaporate. Without external heating, droplets usually shrink faster as they become smaller. The simplest description of this is the $D^2$ law, where the shrinking rate $dR/dt$ is proportional to $t^{-1/2}$ or $R^{-1}$. However, modeling this becomes more complicated when irradiation-driven volumetric heating is considered, and only few studies have investigated the evaporation behavior of levitating droplets under strong irradiation. Here we show the effects of weak and strong irradiation on single, optically levitated, micrometer-sized water droplets. We find that the droplets shrink following distinct accelerating and decelerating regimes, that we characterize through two power laws. Under weak irradiation, the shrinking rate accelerates, similar to the $D^2$ law. Under strong irradiation, however, the shrinking decelerates following the power law $dR/dt\sim R$, i.e., inverse of the $D^2$ law. Between these two regimes, at radii of 3–5 $\mu \mathrm{m}$, a turnover occurs from decelerating shrinking back to accelerating shrinking. Our findings shed new light on droplet evaporation under weak and strong irradiative heating, such as mists under sunshine or fuel droplets irradiated by flames in rocket engines or internal combustion.

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• Drops & bubbles
• Evaporation
• Lasers
• Mie scattering
• Optical levitation