Nonlinear optomechanics with gain and loss: amplifying higher-order   sideband and group delay
  We study the nonlinear optomechanically-induced transparency (OMIT) with gain and loss. We find that (i) for a single active cavity, significant enhancement can be achieved for the higher-order sidebands, including the transmission rate and the group delay; (ii) for active- passive-coupled cavities, hundreds of microsecond of optical delay or advance are attainable for the nonlinear sideband pulses in the parity-time-symmetric regime. The active higher-order OMIT effects, as firstly revealed here, open up the way to make a low-power optomechaical amplifier, which can amplify both the strength and group delay of not only the probe light but also its higher-order sidebands. 
Y. Jiao, H. L\"u, J. Qian, Y. Li, and H. Jing
quant-ph cond-mat.mes-hall physics.optics