Lecture 8: Laser amplifiers
Lecture 8: Laser amplifiers
Lecture 8: Laser amplifiers
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Rate equations<br />
2<br />
R 2<br />
1/ 21 = 1/ sp + 1/ nr<br />
1<br />
sp<br />
nr<br />
1/ 2 = 1/ 21 + 1/ 20<br />
R 1<br />
1<br />
20<br />
1/ nr<br />
: non-radiative decay rate<br />
<br />
<br />
Steady-state populations of levels 1 and 2 can be maintained only if<br />
the energy levels above level 2 are continuously excited by<br />
pumping and ultimately populate level 2.<br />
Pumping serves to populate level 2 at rate R 2 and depopulate level<br />
1 at rate R 1 (per unit volume per second)<br />
=> levels 1 and 2 can attain non-zero steady-state populations.<br />
85<br />
85