A no-core fiber-microsphere resonator for excitation of whispering gallery mode

We demonstrate a whispering gallery mode (WGM) microsphere resonator on a nocore fiber (NCF) tip. The device is fabricated by fusion splicing of a single-mode fiber (SMF) with a short section of NCF, and followed by gluing a microsphere on the arc end of NCF. The incident light propagates from the SMF core to the microsphere via the NCF and when the angle between the SMF-NCF axis and the center of microsphere is appropriate, WGM is excited. The device is simple in structure, easy in fabrication and of low cost, and can be used for temperature sensing with a good sensitivity of 21.34 pm/℃.