Rami Arieli: "The
Laser Adventure" Chapter 4 Section 4, page 14

The stability criterion for laser cavity is:

**In the stability diagram the geometric parameters of the mirrors
are the axes x and y.**

Figure 4.13 show the **stability
diagram** of all laser cavities.

**Figure 4.13: Stability Diagram of all laser cavities.**

In the stability diagram, in figure 4.13,** the dark
region marks the area of stability**.

**The stability region is surrounded
by two hyperbolas defined by the stability criterion.**

A few common cavities are marked on the stability diagram.

**A cavity is stable
if the center of curvature of one of the mirrors, or the position of the
mirror itself, but not both, are between the second mirror and its center
of curvature.**

**Pay special attention for cavities on the edges
of the stability region !**

**For these cavities, the product g _{1}*g_{2} is either
"0" or "1".**