| The study of the nonlinear optical properties of novel nanostructured ion implanted and laser ablation of Silicon is motivated by the need for materials that exhibit large values of the real part of the third order nonlinear susceptibility (chi(3)Re). This property is essential for light controlled phase or refractive index modulation at low power, where the optical properties are used for optical switching devices. Previous nanosecond (ns) measurements indicated values of -2.8 x 10-5 esu (lambda = 532 nm) for chi(3)Re.; The characterization of nonlinear optical properties of the samples were studied by the Z-scan techniques using ∼100 fs pulses. The Z-scan technique is a relatively simple and direct measurement of both the real and imaginary part of chi(3), where the nonlinear refractive index (n 2) is related to chi(3)Re and the nonlinear absorption (beta) to chi(3)Im. Femtosecond pulse excitation measurements were performed to study ultrafast dynamics by inducing nonlinear optical changes, such as photo-induced absorption and measuring the nonlinear response. For fast optical switching applications, a fast and relatively large electronic nonlinearity is required. |
