Mode stability issues in side-pumped relative to end-pumped quasi four-level lasers

Summary form only given.It is now well established that ytterbium´s simple spectroscopy and the low host crystal thermal loading that results from the ion´s minimal quantum defect allow dramatic power scaling. Exactly how much heat is deposited into the host crystal at a given moment is intimately intertwined with the ion´s excitation and de-excitation pathways. An optical resonator´s stability strongly depends on the optical consequences of heat deposition, namely thermal lens and depolarization. It can therefore dramatically depend on the laser dynamics. We show that a side-pumped Yb:YAG rod is much less sensitive to these effects than an end-pumped one.