3. A 800-nm pulsed laser emits one laser pulse every 13 ns. The duration of each pulse is 100 fs. You can treat each pulse as a squared pulse: That is,

the power immediately jumps to its "on" value, stay constant for 100 fs, and then jumps back to zero until the next pulse. In reality, the pulses are more like a Gaussian function. The time-average power of the laser is 2 W. The beam size is 1 mm. Estimate: (1) Energy of each pulse. (2) Energy fluence of each pulse (that is, energy of each pulse per unit area). (3) Number of photons in each pulse. (4) Power, intensity, and electric field when the pulse is "on".