Calculate Laser Pulse Intensity (Optics)

[mecarey]

A laser pulse has a duration of 50 fs (50E-15 s) and an energy of 1 mJ. The laser is focused to an area of 50 micrometers square. What is the peak intensity and peak electric field at the focus?


I previously tried to do this problem with normal intensity equations using

intensity = power / area
and
power = joules/second

but I got a ludicrous answer in the range of 10^20 watts/meter square. My professor told me that my answer is wrong because it is a laser PULSE, not just a laser. Any help? I'm not too sure where to go now and my Optics book doesn't seem to cover laser pulses.

Thanks in advance - Matt

 

[mebond2004]

Hi,

Hope this will help

Av Power = E/T

Peak Power = E/t

Intensity = Av Power/area

where,

E = energy of the pulse (i.e.1 mJ)
T = 1/f (f is the freq of laser pulse)
t = Duration of the pulse
area = 50 micrometers square.