Abstract

It is well known that the nonlinear response of bound electrons in transparent solids occurs on a very fast time scale. Recently, a significant delay of the nonlinear response in the regime of intense (close to the materials damage threshold) femtosecond laser fields was reported [1]. In the regime of weak laser fields, where the response is dominated by the third-order nonlinearity, it is known since a long time that the response is well below 1 fs [2,3], but a finite value of a potential delay could not be reported.

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