Transverse-mode distortions in giant-pulse laser oscillators

It is shown that high-gain giant-pulse lasers can have transverse intensity profiles differing greatly from the steady-state transverse-mode patterns. The transient effects of gain saturation may cause the intensity profile at the output mirror to change rapidly with time. This can lead to non-Gaussian output intensity profiles, short-duration intense regions ("hot spots"), and irregular time behavior. Shortening the cavity length, i.e., increasing the resonator Fresnel number, which is often done to reduce the number of longitudinal resonances, will only enhance these effects.