Observation of order and chaos in a nuclear spin–flip laser

Experimental observations and computer simulations of the nonlinear response are discussed for a single-mode, solid-state, nuclear spin–flip, ruby nuclear-magnetic-resonance (NMR) laser. A theoretical model is derived that is based on the classical Bloch equations and that demonstrates one-to-one correspondence to a homogeneously broadened, single-mode ring laser. Experimental evidence is presented for limit cycle behavior, sequences of sub-harmonic bifurcations, transitions to chaos, noisy bands, windows of regular behavior, intermittency, abrupt transitions between different basins of attraction, and hysteresis when a physical system parameter of the NMR laser is modulated at a low frequency. First experimental results are shown for a NMR laser with an external, detuned high-frequency signal below the injection-locking threshold. In this region, the output exhibits transitions from regular to chaotic oscillations and phase-locked spiking somewhat of the nature of what has been theoretically proposed for optical systems.