A Promising SPR Sensor with Single mode- Multimode-Single mode Fiber Embedding Microcavity

A cascaded fiber device is proposed basing on a cascaded structure. The device is designed with single mode- multimode-single mode fiber, with a microcavity in the central position of MMF. To get higher energy on the surface of the device, the structure is optimized, which means a strong SPR signal would be excited and a low detection limit would be get. Further, the transmission modes in cavity wall are analyzed, the fundamental modes are found to be the dominant modes.