Module 7 : Laser- I
Lecture   : Introduction - Basics of stimulated emission
 

Planck's formula for the radiant energy density is given by

$\displaystyle u(\nu)d\nu = \frac{8\pi h\nu^3}{c^3} \frac{1}{e^{h\nu/kT}-1}d\nu$
  \includegraphics{laser5.eps}
  The figure given here showns the radiant intensity distribution, $ I(\lambda)d\lambda$which is obtained by multiplying $ u(\lambda)d\lambda$by a factor $ c/4$arising out of averaging over the angles and considering the outgoing waves.
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