Conclusion

The resonators study is a necessary first step for any laser realization. In this course, we only described simple passive structures : for more complex systems, several software have been developed to easily simulate any type of cavity without carrying simple but painful calculation. It is then possible to take into account some more complex effects such as :

• influence of the finite size of the mirrors : the diffraction plays a key role if the mirrors are very small. In this case the relevant term is the Fresnel' s number where a1 and a2 are the cavity mirrors radii (not the radii of curvature !). If N >>1, you could neglect the diffraction effects.

• Astigmatism for the off-axis systems (as V-shaped cavities for example)

• Influence of the amplifying medium (active cavity) : heating effects, dynamic behaviour...

• Polarization effects

For a more complete review on the topic I suggest the following references : [ , ]