Slowing probe and conjugate pulses in potassium vapor using four wave mixing.

We present an experimental study on ultraslow propagation of matched optical pulses in nondegenerate four wave mixing (FWM) in hot potassium vapor. The main figures of merit, i.e. fractional delay and fractional broadening, are determined to be 1.1 and 1.2, respectively. The latter two are approximately constant for the broad range of the two photon detuning. Input probe pulses between 20 ns and 120 ns can be delayed within broad range of the gain. The results are compared with the preceding works for Rb and Na.