Difference between stable and unstable resonators

Difference between Stable and Unstable Resonators:

1. The oscillating beam is converged in stable resonator while in unstable resonator is spreads out of the the resonator.


2. In stable resonator laser output is from the centre of optical axis while in unstable resonator laser output comes from the edge of the output mirror.


3. The field is confined to the axis in stable resonator while it is not so in unstable resonator.


4. Stable resonators are used for low power lasers while unstable resonators are used for high power lasers.


5. In stable resonator these remains risk of breakage of the m  irrors while it is reduced to unstable resonators.


6. The mode volume is is small in stable resonators while it is large in unstable resonators.


7. The geometrical losses are large in unstable resonator in comparison to stable resonators.


8. In unstable resonators better beam quality may be achieved in comparison to stable resonators.