Theoretical Studies On The Microsphere Resonator Coupled By Biconical Tapered Fiber And The Fabrication System Heating By CO₂ Laser

In this paper, we had studied the CO₂ laser fabrication of microsphere resonators coupled by biconical tapered fibers. The integrated fabrication system of melt-drawn biconical tapered fibers and microsphere resonators using a CO₂ laser as its heat source has been developed. Silica micospheres and glass microspheres doped by Nd+3 had been made using this fabrication system. The sizes of the microsphere and biconical tapered fiber waist had been discussed for optical devices. The characteristic of the coupling between the microsphere resonator and the biconical tapered fiber had been studied.In the first part, we had a general review of the history of microsphere resonance in theory and experiment study. The developments of the coupled microsphere system had been introduced. It had been approved by experiments that the biconical tapered fiber is a good energy exchange device for microspheres. The biconical tapered fiber had been selected as the coupler of the microsphere resonance in our study. Several fabrication methods of the biconical tapered fiber and the microsphere had been compared. The precise fabricating technique of CO₂ laser had been used in our experiments.Secondly, the characters of the microsphere resonance and the biconical tapered fiber had been analyzed separately. The best ranges of the radii of the microsphere resonance and the biconical tapered fiber for optical devices had been given. Using the weakly guided mode, the normalized radial phase constants (U) and the propagation constants for biconical tapered fiber with different waist radii had been calculated precisely. The correspondence relationship for radii had been given when the tapered fiber as pump method to phase-matched excite the WGM laser in the microsphere. By using the H. J. Shaw's method for studying the single-mode fiber directional couplers and...