Efficient Dual-Wavelengths Continuous Mode Lasers by End-Pumping of Series Nd:YVO4 and Nd:GdVO4 Crystals and Speckle Reduction Study

In this paper, diode pumped solid state (DPSS) lasers based on end-pumping series N d : Y V O 4 and N d : G d V O 4 crystals were studied. Dual-, tri-, and quad-wavelength emissions were achieved. In the dual-wavelength emission operation, an optical-to-optical efficiency (O-O) of 48.9% and the power instability was 0.4% were obtained. These are the most efficient and compact lasers operating in continuous wave mode reported to date with series crystals. Besides this, the effect of changing power ratio between the output laser powers on speckle reduction was investigated for the first time. In addition, tri and quad wavelength emissions were achieved with a reasonable efficiency simply by optimizing the cavity parameters.