Multicolor nonreciprocal optical amplifier with spinning active optomechanics

We propose to achieve a multicolor nonreciprocal optical amplifier, a crucial device in optical communication and information processing, by spinning an active resonator. We show that in such a device, due to the interplay of the Sagnac effect and the optical gain, nonreciprocal signal amplification can be realized, accompanied by a giant enhancement of optical group delay from $0.3\mathrm{ms}$ to $35\mathrm{ms}$ in a chosen direction, which is otherwise unattainable in a passive device. Also, coherent amplification of higher-order optical sidebands and a slow-to-fast light switch can be achieved by tuning both the pump power and the spinning velocity. Our work provides a unique and accessible way, well compatible with other existing techniques, to realize multicolor nonreciprocal optical amplifiers for more flexible control of optical fields.