Squeezed light generation in cascaded optomechanical systems

Abstract We theoretically investigate the enhancement of the degree and bandwidth of squeezed states of light generated in cascaded optomechanical (OM) systems. With the obtained recursion relation of the generalized output quadratures, it is possible to realize cascaded OM systems operated simultaneously in a deamplification situation for the same quadrature with a frequency-dependent phase shift between cascaded systems. Due to the cumulative OM interaction, the degree of squeezing can be significantly improved and nearly independent of frequencies. Thus the squeezing frequency band is notably broadened. Moreover, the squeezing bandwidth can be further broadened through tuning the detunings between laser and cavity frequencies. Finally, the influence of optical losses on squeezing due to the inefficient transmission between cascaded systems is also taken into account, which degrades the squeezing via introducing uncorrelated vacuum noises. However, a better squeezed state is still achievable compared to that generated in single OM system.