Micrometer-Size Droplets as Optical Cavities: Lasing and Other Nonlinear Optical Effects

摘要

The morphology of a droplet enhances the internal and external intensities at specific locations and produces high Q-factor feedback for specific wavelengths of emission generated inside a droplet. Coherent nonlinear emissions have been observed from micrometer-size droplets along with other nonlinear effects such as wavelength broadening due to the intensity-dependent refractive index. Physical and chemical properties of the droplet can be deduced from such coherent emissions. Laser-induced droplet explosion and a laser-supported detonation wave result at input intensity levels higher than those necessary to observe such nonlinear effects. The use of spatially resolved spectroscopy to analyze emissions resulting from microexplosion has provided some preliminary details about droplet and air breakdown mechanisms.