Research On WGM Microsphere Resonator Based On Open Microcavity

With the development of optical fiber technology in modern society,the miniaturization and integration of optical devices have become a hot issue that researchers are concerned about.Among them,optical microcavities based on whispering gallery mode(WGM)have important applications in optical communication,optical fiber sensing and other fields due to their excellent characteristics such as small mode volume,high quality factor,easy integration,and convenient fabrication.This paper mainly studies the new coupling structure of whispering gallery mode microcavity and optical fiber.The introduced WGM resonators mainly include:1.A WGM resonator based on the coupling of a tapered fiber and a micropillar cavity is proposed,wherein the tapered fiber is prepared by heating and drawing a standard single-mode fiber into a fiber taper.Then we use UV glue to fix the tapered fiber and the micro-column cavity on the glass slide.One end of the tapered fiber is used as an input coupler and the other end is used as an output coupler.The self-built three-dimensional mobile platform is used to adjust the coupling position of the tapered optical fiber and the micro-column cavity.The study of this device lays a theoretical foundation for the follow-up research.2.An open-cavity WGM microsphere resonator based on multimode fiber is proposed.An open air cavity is fabricated on the multimode fiber by femtosecond laser micromachining and fusion technology,and the microsphere is released by the fiber taper.Into the air cavity,adjust its relative position and excite the WGM mode,the device obtains the WGM transmission spectrum with a quality factor of 2×10~5.3.An open-cavity WGM microsphere resonator based on single-mode fiber is proposed.Due to the large insertion loss of the device prepared by multi-mode fiber,and there are many modes in the multi-mode fiber,the spectral lines are slightly disordered.The multi-mode fiber is improved into a single-mode fiber,and the single-mode fiber is used to prepare an open cavity that is just tangent to the core of the single-mode fiber,which reduces the insertion loss of the device and improves the mechanical strength of the device.It is placed in an open cavity and coupled with a single-mode fiber core to excite the WGM mode.In this paper,an in-fiber WGM microsphere resonator is proposed,which has the advantages of high integration,simple fabrication,and compact size.