Exper Imental Research On Tunable Er～(3+)-doped Optical Fiber Ring Resonator

Because of the gain mechanism in the resonator, the active fiber resonatorsshow polymorphic characteristics in the different working state. Under thethreshold, the active fiber ring resonator can be used as optical filter. Upperthe threshold, it became fiber ring laser. In this dissertation, the polymorphiccharacteristics of tunable Er'+-doped fiber ring resonators below, near andupper tllresllold are chiefly analyzed.(l) Ill tlle second cllapter of this dissertation, the behaviors of the activeliber resonators are studied by both theoretical and experimel1tal ways,when it is under the threshold. Based on the structure of all optical activefiber ring resonator, dual-tunable Er3+-doped optical fiber ring resonatorfilter is investigated by adding a tunable bandpass filter to change itswavelength. Its finesse can also be tunable by adjusting the pump power.The wavelength tuning range of the dual-tunable fiber ring resonatorfilter is 39nm,frOm l526nm to l565nm. Its finesse is independent of thewavelengtl1 of input laser.(2) ln the third chapter of this dissertation, the behaviors of intra-cavityamplified spontaneous emission (ASE) light in the active fiberresonators are firstly studied by both theoretical and experiment8l ways,when it is operating near the threshold. Just below threshold, consistel1tto theoretical analysis, there are numbers of comb-like narrow linewidthlights due to resonating of ifltr8-cavity ASE light. Novel experimentalresults of the Erbium-doped-fiber ring resonator behaviors operatingnear threshold are reported in the chaPter. The reaction of threshold onlinewidth of ring's outPut light is pointed out. This provides a newauxiliary method to determine the threshold. We also propose a newsubsidiary method fOr finesse measurement based on selfhomodyne byx m.using of resonating of the intra-cavity amplified spontaneous emission(ASE) light, without extemal light source.(3) ln the fourth chapter of this dissertation, a tunable single-longitudinal-mode Erbium doped fiber ring laser is achieved by using the very narrowbandpass characteristics of the self written grating fOrmed in a section oferbium doped flber withoat undergoing pumping by stable standingwave in it. Tl1e tunable laser's wavelength tuning range is 40nm,froml 523.79llm to l563.92nm. lts lil1ewidth is less than 2.33KHz in its fullwavelength tuning range. It is a very good linear-polarization laser, andits outPut is characterized by obvious optical bistability.