Super continuum GVD calculation

[paranoidom]

So i seem to have run into a problem. I found a way to accurately measure white light pulses but i still need some help doing the math. The information i have is:

1) wavelength vs time graphs [of the white light]

2) Material - using 2 fused silica prisms to compress the white light

The math I've been following is from Diels - ultrashort laser pulse phenomena pg 100-117 (latest edition) - pdf attached

Q: How do i calculate GVD of the pulse in the graph above? Please let me know if you have any idea - i am fairly new to theoretical aspects in the field!

Thanks!

UPDATE: The derivation of GVD from Vg[group velocity] is pretty clear. But in order to obtain the GVD of the graph above, i need the Vg from the information provided[the graph]. Thats where I am having trouble:

The graphs gives us:
[w=omega=angular freq]
dt/dw [$$\lambda$$=2*$$\pi$$*c/w]
dw/dk (i.e. Vg) =dt/dw * dk/dt - where k==[w*n(w)]/c and w=w(t)

this seems like a loop!

 

[Valerie Park]

I'm sure there is a way to find Vg by plotting the graph above and then finding the slope at each point but how could i generalize this for a range of different pulses?Any help would be appreciated!