Real-time measurement of temperature distribution inside a gain medium of a diode-pumped Er/Yb 1.55 μm laser.

A scheme to measure temperature distribution inside a gain medium of a diode-pumped solid-state laser is proposed based on the fluorescence intensity ratio technique. By recording the temperature-dependent upconversion fluorescence related to the H2→I4 and S4→I4 transitions of Er, the real-time temperature distribution inside an Er:Yb:LuAl(BO) crystal end-pumped by a 976 nm diode laser can be measured while a 1.55 μm laser is operating.