Nonlinear Optical Response of Chinese Teas Probed by Spatial Self-Phase Modulation

Chinese tea is the most highly consumed beverage globally. Its different types exhibit a strong nonlinear optical response as probed previously by Z-scan technique at various time scales. In this work, infusions of commercially available black, green, and white Chinese teas, prepared by running one cycle of a Soxhlet extraction, were studied by spatial self-phase modulation of a CW laser; each sample was found to have a different nonlinear refractive index n2, which can be used to distinguish these teas.