Nonlinear Kerr Material and Lorentz Dispersion (urgent)

Hi all,

I am planning on simulating a 2D nonlinear photonic crystal using silicon dioxide as my material, and there are four choices for the type of nonlinear model to create: 2nd order, 3rd order, Kerr, and Raman. When I select the Kerr model, it gives me three parameters to enter:
-Relative permittivity
-Response Time
-Permittivity
I found the relative permittivity of silicon dioxide, but I am unable to find the response time and Kerr permittivity anywhere. Can anyone send me a source which lists these values for silicon dioxide? If not, can you explain to me how I might be able to find these values, not only for silicon dioxide but for any material?

Also, due to the Kerr intensity-dependent equation, n = n(0) + n(2)I where n is the refractive index, n(0) is the linear refractive index, n(2) is the nonlinear refractive index, and I is the intensity, it is necessary for me to know the linear and nonlinear refractive indices of silicon dioxide in order to determine the intensity of the input wave. Is there any way for me to find these values using the permittivity and response time values stated above?

One final question, to simulate the nonlinear 2D photonic crystal, would I need to turn Lorentz Dispersion on or off? If I need to turn it on, how do I determine which values I need to input in order to simulate the photonic crystal correctly?

Thanks so much for your attention