Question

A laser source has a bandwidth of 30GHz (a) Calculate the coherence length of the source b) What is the time separation of sections of the light wave that can still interfere? source, can have?

Answer 1

Explanation:

It is given that,

Bandwidth of a laser source, $f=30\ GHz=30\times 10^9\ Hz$

(b) Let t is the time separation of sections of sections of the light wave that can still interfere. The time period is given by :

$T=\dfrac{1}{f}$

$T=\dfrac{1}{30\times 10^9}$

$T=3.33\times 10^{-11}\ s$

(a) Let h is the coherence length of the source. It is given by :

$l=c\times T$

c is the speed of light

$l=3\times 10^8\times 3.33\times 10^{-11}$

l = 0.0099 m

Hence, this is the required solution.