Period-doubling lasers as small-signal detectors

Near the onset of a period-doubling bifurcation a parametrically modulated NMR laser has been used as a detector of weak input signals with a strongly peaked response curve centered near half the modulation frequency. The maximum sensitivity increases the closer the bifurcation point. A Bloch-Kirchhoff model with realistic parameters has been used for computer simulations. Experiments and theory are in fair agreement. The results suggest that any parametrically modulated laser device could be used as a small-signal detector for selected frequencies.