E-field of a laser pulse and Intensity

1. Jun 6, 2010

PhysMaster

Hi,
What is the equation for a E field of a single pulse of a laser?
If that laser is shined onto say a grating spectroscope (square law detector), how can I go about deriving an expression for Intensity as a function of frequency at the output of the spectroscope?

I know that the square law detector will measure Energy which is the square of the E field (and some proportionality factor that I don't know).
I also know Intensity equation, I = 1/2 Epsilon * c * E^2 where Epsilon is the permittivity in vacuum. But that doesnt seem to apply here since it has no dependence on frequency.

Any help is much appreciated.

2. Jun 6, 2010

Staff: Mentor

Frequency and intensity are independent of each other, in general. Why do you think there should be a relationship between them?