Using reservoir-engineering to convert a coherent signal in optomechanics with small optomechanical cooperativity

Optomechanical dark mode plays a central role in effective mechanically-mediated conversion of two different cavity fields. In this paper, we present a more efficient method to utilize the dark mode to transfer a coherent signal. When an auxiliary cavity mode is exploited, two approaches are proposed to effectively eliminate the optomechanical bright mode, and only the optomechanical dark mode is left to facilitate state transfer. Even with small cooperativity and different losses for the two target modes, the internal cavity mode-conversion efficiency can also reach unity.