Studies on simultaneous dual wavelength operation at 912.2Â nm and 914Â nm from dual gain diode-pumped Nd3+ doped vanadate laser

A laser is constructed comprising of Nd3+ doped yttrium vanadate (Nd:YVO4) and gadolinium vanadate (Nd:GdVO4) in order to obtain simultaneous dual wavelength operation at 914 nm and 912 nm emitted by the respective crystals under 4F3/2→4I9/2 laser transitions. The performance of the laser is studied experimentally and analyzed using laser rate equation model incorporating the cross saturation terms. The simulated trend of variation of output power at 912 and 914 nm as a function of pump power agrees reasonably well with the experimental data and confirms that the saturation of gain at Nd:GdVO4 crystal by the 914 nm is much stronger than the saturation of gain at Nd:YVO4 crystal by the 912 nm. It has been found that to obtain simultaneous dual wavelength operation the relative gain at the Nd:GdVO4 crystal should be considerably higher than that at the Nd:YVO4 crystal. At a pump power of 29.7 W and 22.6 W applied to Nd:GdVO4 and Nd:YVO4 crystals respectively, 1.3 W of output power at 912.2 nm and 1.7 W of output power at 914 nm was obtained simultaneously. The frequency difference of the two wavelengths is 0.73 THz and the state of polarization of the two wavelengths can be easily varied by changing the relative orientation of the c-axes of the crystals.