Multiple-channel dynamic bandpass filter via radiation modes-assisted transparency in a side-coupled SNAP microcavity

We experimentally and theoretically demonstrate a tunable bandpass filter based on the optically induced transparency enabled by dynamical interference of continuous radiation modes and localized whispering gallery modes (WGMs) with a Surface Nanoscale Axial Photonics (SNAP) platform. The tunability in bandwidth and power transfer efficiency is achieved by scanning the microfiber which achieves a high power transfer efficiency up to 1.43, high out-of-band rejection of ~31 dB, and bandwidth tunability of 30.6 MHz~2.32 GHz. The combination of easy alignment, fiber compatibility, high efficiency, and robust wide-range tunability facilitates applications ranging from quantum optics to photonic networks.