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

Using Planck's law one can show that the total power emitted by a blackbody at a temperature $ T$is given by

$\displaystyle U = \sigma T^4$
where $ \sigma$is called Stefan's constant, which has a value $ 5.67\times 10^{-8}$J-K $ ^4$/m $ ^2$.

 

The emitted radiation has a peak at a wavelength $ \lambda_{max}$give by Wien's Displacement Law
$\displaystyle \lambda_{max}T = 2.9\times 10^3\ {\rm m-K}$
For instance, a blackbody at a temperature of 5000K has a radiation peak at 580 nm, which is near the middle of the visible region.

  \includegraphics{laser6.eps}
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