Fig. 2
(a) Probe transmission and (b) generated conjugate beam spectra obtained by frequency-scanning the probe-seed in 85Rb (red curves) and 87Rb (blue curves) atoms. For 85Rb, besides the linear absorption, a narrow and strong parametric gain feature is observed at ± 3.036 GHz relative to the pump frequency, set at 0.9 GHz towards the blue-detuning from the 85Rb 5S1/2, F = 2 to 5P1/2, F = 3 transition. Similarly, for 87Rb, in addition to the linear absorption, distinct parametric gain features are observed at ± 6.835 GHz from the pump frequency, which is tuned to 1.3 GHz blue-detuned from the 87Rb 5S1/2, F = 1 to 5P1/2, F = 2 transition.
