Polarization bistability associated with ⁴F_3/2→⁴I_11/2 and ⁴F_3/2→⁴I_13/2 transitions in Nd:YVO₄ laser with intra-cavity periodically poled lithium niobate Bragg modulator

We experimentally demonstrate polarization bistability in a dual-wavelength Nd:YVO₄ laser at 1064 nm (⁴F_3/2→⁴I_11/2) and 1342 nm (⁴F_3/2→⁴I_13/2) by using an intra-cavity electro-optic periodically poled lithium niobate (PPLN) Bragg modulator to control the loss at 1064 nm. An inverse hysteresis switch was observed between 1064 nm and 1342 nm lasers with orthogonal polarizations by increasing and reducing the loss induced by the PPLN. The size of the hysteresis increased with increasing pump power. This paper provides an explanation based on cross-gain saturation for this bistable behavior of polarization.