Design and characterization of a flexible diode pumped solid state laser neodymium orthovanadate

Abstract

The main goal of this research is to determine temperature variation of stimulated emission cross section of laser crystal through alternative method. Neodymium-doped yttrium vanadate (Nd:YVO4) laser crystal has been utilized as the gain medium. A 808 nm laser diode was employed as the pumping source. A laser system was designed and then a prototype was created. Performance of the laser system was quantified with 97 % reflective at 1064 nm output coupler. It was found that slope efficiency and threshold power of the system were 46.9 % and 0.109 W respectively. The focal power of the laser crystal was varied with absorbed pump power at a rate of 0.228 D/W. From output fluorescence spectrums recorded at various crystal temperatures, variation of linewidth, wavelength and intensity of 1064 nm emission were determined. The rate of change of linewidth, wavelength and intensity with temperature were 5.4 pm/oC, 3.7 pm/oC and 0.075 arb. unit/oC respectively. Through spectroscopic method, stimulated emission cross section variation with temperature was found to be -0.462 %/oC with respect to stimulated emission cross section at 20 oC. For stimulated emission cross section determination through performance method, larger pump beam radius and 70 % reflectivity at 1064 nm output coupler were used. To obtain linear graph, a graph of Pout/f1 against Pabs was drawn. At 30 oC, gradient of the graph, threshold power and cavity loss were found to be 46.6 %, 0.760 W and 6.6 % respectively. Through performance method, stimulated emission cross section variation with temperature was found to be -0.447 %/oC with respect to stimulated emission cross section at 20 oC. The change of stimulated emission cross section with temperature obtained through performance method is in good agreement with spectroscopic method.