Thermal sensitivity of red diodes?

Hi forum;

I recently got my hands on quite a large red laser diode. I am not sure how powerful it is, /several watts at the very least/, but, the threshold current is 4.5A, and my power supply can only do 5 :-)

>>Photo of diode<<

Nonetheless, I have noticed a very strange characteristic with this laser diode. Its output power reduces, substantially, if it is even a tad bit warmer than ambient.

I have not noticed this, with 445 (InGanAs) chemistries. Does anyone know why a red diode would behave this way?