As per my other thread, I need to replace an Nd:YVO4 rod from my engraver's laser head. The original rod is diffusion bonded with a 2mm long undoped YVO4 section, bonded to a 10mm long doped section at probably 1.1% as this seems to be the most common. The face dimensions are 4 x 4mm.
Many manufacturers list stock rods of 3x3mm and a lot of manufacturers offer custom rods; my enquiries so far have effectively been 'how many thousands do you want', in as much as after replying that I only need 1 to 3 items (so spare plus an extra in case of accidents), it all goes quiet.

I am considering if a 3mm square section rod could be used, but I am concerned about the power levels; the rod is mounted in a cut out in a copper heatsink with indium foil for heat transfer; I could add copper shims of 0.5mm on all 4 sides to deal with the cooling problem, but I am mainly concerned about the damage thresholds; the laser is end-pumped with 30W of 808nm and is Q switched, producing peak powers of 20kW at 1064nm, according to the rating plate. Would this be excessive for a 3x3 rod?