Nonlinear Chinese tea
In a recent report, Hong-Jun Zhang and co-workers from the Institute of Physics, Chinese Academy of Sciences, report on strong nonlinear Kerr effects in Chinese tea, herbal medicine, and solutions of chlorophyll. They describe observation of self-focusing and self-phase modulation at powers around 5 mw, using a He-Ne laser. Their observed time constant is of the order of 100 msec and they calculate a nonlinear Kerr coefficient of about 3 x 10-5 e.s.u. Their solution is contained in a sample cell of 10 mm length. Illumination is by means of a 2 mm laser beam focused by a 30 mm lens into the cell.
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