A pulsed laser emits rectangular pulses of width 1 nanosecond at a repetition rate of 1 kHz. If the average power output is 1 mW

Q. A pulsed laser emits rectangular pulses of width 1 nanosecond at a repetition rate of 1 kHz. If the average power output is 1 mW, the average power over a single pulse duration, in watts, is

             (A) 1               (B) 10                          (C) 100                        (D) 1000

Ans: 1000

Sol:

The underlying concept here to be used is that the energy is not a function of time

Hence, Eavg = Epeak

Calculations

Pwidth = 1 nano sec,

Pulse laser frequency = T = 1/f = 1 msec

Energy of laser pulse width=E/T