On-Chip Photonic Transistor Device and Biomolecule Mass Sensor Based on a Whispering Gallery Mode Cavity Optomechanical System

Whispering gallery mode (WGM) cavities, due to their high-quality factors, small mode volumes, and simple fabrications, have potential applications in photonic devices and sensing. In this paper, we present an all-optical transistor based on a coupled realistic WGM cavity optomechanical system. In the system, the transmission of the signal field is manipulated by the optical control power, and the signal field can be efficiently attenuated or amplified depending on the power of a second gating (control) field, which indicates a promising candidate for single-photon transistors. In addition, we theoretically propose a mass sensor based on this WGM cavity optomechanical system. The mass of external biomolecules (such as smallpox virus) deposited onto WGM cavity can be measured conveniently by tracking the mechanical resonance frequency shifts due to mass changes in the probe transmission spectrum. Through detecting the mass of viruses, the kinds of different viruses can be identified. This WGM cavity optomechanical system may have potential chip scale applications in quantum information processing, quantum measurement, and on-chip sensing devices.