Question

Pulsed lasers used in science and medicine produce very short bursts of electromagnetic energy. If the laser light wavelength is 1062 nm (this corresponds to a Neodymium-YAG laser), and the pulse lasts for 34 picoseconds, how many wavelengths are found within the laser pulse?
How short would the pulse need to be to fit only one wavelength?

Answer 1

Explanation:

Given that,

Wavelength of the laser light, $\lambda=1062\ nm=1062\times 10^{-9}\ m$

The laser pulse lasts for, $t=34\ ps=34\times 10^{-12}\ s$

(a) Let d is the distance covered by laser in the given by, $d=c\times t$

$d=3\times 10^8\times 34\times 10^{-12}$

d = 0.0102 meters

Let n is the number of wavelengths found within the laser pulse. So,

$n=\dfrac{d}{\lambda}$

$n=\dfrac{0.0102}{1062\times 10^{-9}}$

n = 9604.51

(b) Let t is the time need to be fit only in one wavelength. So,

$t=\dfrac{\lambda}{c}$

$t=\dfrac{1062\times 10^{-9}}{3\times 10^8}$

$t=3.54\times 10^{-15}\ s$

Hence, this is the required solution.