Efficient parametric non-degenerate four-wave mixing in hot potassium vapor

We have observed high gains of the probe and the conjugate beams in non-degenerate four-wave mixing in hot potassium vapor, using a double-Lambda configuration at the D1 line of the (39) K isotope. Gains of up to 82 for the conjugate beam and 63 for the probe beam have been achieved. Higher gains were obtained than with other alkali atoms under comparable experimental conditions due to lower ground state hyperfine splitting in the potassium atom. Experimental parameters for maximal gain have been determined. Notable gains are achieved at low pump intensities (similar to 10 W cm(-2)) that are attainable even by conventional laser diodes. Due to their high gains, the probe and the conjugate beams may be suitable for utilization in quantum correlation and relative intensity squeezing experiments.