Thermal effects in end‐pumped Nd:phosphate glasses

Thermal effects in continuous‐wave end‐pumped Nd:phosphate glass were studied. Thermally induced fracture was due to the tangential stress at the peripheries of the samples near the front entrance. For pump beam size much smaller than the diameter of a cylinder rod or the thickness of the cross section of a rectangular slab, the critical pump power causing thermal fracture depends only on the heat absorbed per unit length. The focal length of thermal lensing was measured to be ∼1 cm at an incident pump power of 2 W. Thermally induced birefringence significantly affected the laser oscillation.