Accurate and efficient modeling of the transverse mode instability in high energy laser amplifiers

We study the transverse mode instability (TMI) in limit where a single higher-order (HOM) is present. demonstrate that when beat length between fundamental and HOM small compared to scales on which pump amplitude optical amplitudes vary, TMI three-wave mixing process two modes with phase-matched component of index refraction induced by thermal grating. This usual applications, this identified as stimulated Rayleigh scattering (STRS) process. model based equations can have large computational advantage over current coupled methods must use longitudinal step sizes are length.