Efficient laser heating of transparent liquids using multiphoton absorption

Abstract

Abstract At high laser intensities, otherwise transparent liquids can absorb strongly by the mechanism of multiphoton absorption, resulting in heating and temperature increases orders of magnitude greater than that from classical, low-intensity mechanisms. The use of multiphoton absorption provides a new mechanism for significant, controlled energy deposition in transparent liquids, which is important for a variety of laser-liquid technologies. This work develops a microscopically based model of heating during multiphoton absorption in liquids induced by high-intensity, short-pulse laser radiation. The dependence on laser pulse parameters and liquid properties is discussed, and pure water exposed to 266 nm laser radiation is investigated both theoretically and experimentally. A novel heating mechanism for water is proposed that uses multiple- wavelength laser pulses, and applications where multiphoton absorption may be incorporated are discussed.