Experimental determination of fractional thermal loading in an operating diode-pumped Nd:YVO4 minilaser at 1064 nm

摘要

A practical in situ method is described and used for determination of the fractional thermal-loading parameter η↓(h) in an operating diode-pumped Nd:YVO↓(4) minilaser at 1064 nm. Readily applicable to the thermal characterization of other solid-state media, the method is based on the fact that thermally induced lensing will cause the laser oscillation to be quenched at a critical pump power whose magnitude depends on the cavity configuration, thermo-optical properties of the gain medium, and, in particular, on the value of #. In the experiments described here, a 0.5-mm-long coated Nd:YVO↓(4) crystal with B-at. % Nd concentration was used to construct the diode-pumped laser with a fiat highly reflecting end mirror and an intracavity lens. For the method to be effective, the resonator was set up close to the edge of the stability range. Above the oscillation threshold, the pump power at which lazing was quenched because of the onset of the thermally induced resonator instability was measured as a function of the intracavity lens position. A numerical model that accounted for absorption saturation and pump-induced thermal lensing was then used to analyze the experimentally measured data with η↓(h) as an adjustable parameter. The average best-fit value of η↓(h) was determined to be 0.40 with an estimated statistical variation of 8%. #1999 Optical Society of America OCIS codes: 140.3070, 140.3530, 140.