Third-order optical sum-frequency generation in micrometer-sized liquid droplets

A series of discrete emission peaks is detected from single micrometer-sized droplets. The series starts at the blue third harmonic of the input IR radiation and extends to the red as a result of four-wave mixing of the input radiation and the multiorder stimulated-Raman-scattering radiation. The detected third-harmonic intensity from a single liquid droplet is several orders of magnitude larger than that from an optical cell containing the same liquid.