Hysteresis loop and pattern from the dual-wavelength competition in an Nd:YVO4 laser with an intracavity periodically-poled lithium niobate Bragg modulator

This study demonstrates hysteresis loop and pattern formation in a Nd:YVO4 laser at 1064nm (⁴F_3/2→⁴I_11/2) and 1342nm (⁴F_3/2→⁴I_13/2) with an intracavity electro-optic periodically poled lithium niobate (EO PPLN) Bragg modulator by using a T-type cavity configuration. Based on these dual wavelengths sharing population inversion in the same upper energy level to lase, the transmission, T_p, of EO PPLN was chosen as the controlling parameter to explore the dynamics of dualwavelength competition. A hysteresis loop occurred when the extracting efficiencies of dual wavelength were near equivalent. When the pump power was 9.0 W, the hysteresis loop was observed in the region of the transmission of PPLN between T_p=64.88% to Tp=84.47%. The slope efficiencies were 25.96 and 3.92% and the thresholds were 2.5 and 3.5 W for the wavelengths of 1064 and 1342 nm, respectively. The width of the hysteresis loop increased when the pump power increased. Moreover, the hysteresis loop accompanied with the variation of the pattern formation. A high-order transvers mode was easily observed at 1342 nm light, but a simple spot existed for 1064 nm light. Apparently, the role of gain competition is worthy to deeply explore.