3.5 Lasers Flashcards
1
Q
Define population of atoms
A
All atoms with a particular quality
2
Q
Define population inversion
A
If there are two states each with n atoms, and e energy, there is a population inversion if e2 > e1 and n2 > n1
3
Q
Define pumping
A
Transferring particles to a high energy state to achieve a population inversion
4
Q
How is light from a laser coherent?
A
- Spatial coherence: different points across the width of the laser beam are in phase with one another
- Temporal coherence: there are no sudden changes of phase
5
Q
Define stimulated emission
A
Where photon emission is triggered by other photons
6
Q
Define optical pumping
A
Raising the state from the ground state to the pumped state using photons of energy Ep-Eg
7
Q
Define amplifying medium
A
The material in the laser in which a population inversion exists
