Novel Lasers Based On Micro-nano Structure

The progress of all-optical information processing technology has greatly promoted the development of optical precision devices,especially those optical micro devices with simple optical structure,small size,low manufacturing cost and more stable performance.The optical resonator based on micro-nano structure is a very important optical component.The micro-ring fiber resonator which has an optimized size,combined with the effect of four-wave mixing,has good interference filtering performance and could be used to realize a novel type of multi-wavelength fiber laser.The micro-ring resonator has high Q value,small mode volume,and typical mode of optical echo wall.It could be widely employed in many fields,such as optical sensing,micro laser manufacturing,ultra-narrow linewidth filtering and all-optical communication.Therefore,the optical micro-nanostructure with high integration and small volume has become one of the research hot spots in the field of optics.In the field of chemical materials,upconversion nanoparticles doped with monodisperse lanthanide elements have stable photochemical properties,such as sharp and stable emission peak,relatively long lifetime in excited state level,high photobleaching resistance,long Stokes shift and low material toxicity,making it the best candidate medium for laser generation.Upconversion nanoparticles can convert nearly infrared light into visible or ultraviolet light,which promotes its applications in biological cell labeling and monitoring,medical imaging,display devices,anti-counterfeiting,laser and other fields.However,upconversion fluorescence still has the disadvantages of low luminescence efficiency and wide fluorescence bandwidth.The thesis is mainly focused on combining the upconversion nanoparticle materials with the micro-nano optical resonator to convert the wide bandwidth upconversion fluorescence into an upconversion laser with higher power density and narrow bandwidth.New breakthroughs have been made in the fields of physical micro-nano optics and chemical materials.The main research of this thesis is as follows:1.A brief overview is given about the development history of optical micro-nanostructures,and the principle of optical echo wall mode.Based on the classical microsphere cavity,the theoretical formulas have been derived from the Maxwell equations.The physical parameters have been introduced,such as quality factor and mode volume to measure the performance of the microcavity.Based on the micro-ring structure utilized in the experiment,the coupling structure composed of a micro-ring and a long waveguide has been numerically simulated and analyzed by FDTD Solutions.2.The process of making ring resonators by the optical fiber melt taper machine has been described in detail.The micro-fiber resonator has the characteristic of wavelength filtering.Based on it,a novel 2-?m thulium-doped multi-wavelength fiber laser due to the four-wave mixing has been realized.The output spectra of the fiber laser under different pump powers has been illustrated and analyzed.3.The concepts of upconversion nanoparticle materials and upconversion luminescence are introduced,including five energy level transition mechanisms in the process of upconversion luminescence.The preparation process of sodium tetrafluoroyttrium upconversion nanoparticles solution used in the experiment has been described.The fluorescence spectra and the gain characteristics of the solution have been discussed.Combined with the echo wall mode of the micro-ring resonator and the upconversion nano-gain medium,a novel upconversion nano-laser with blue laser output has been realized,of which the experimental results are analyzed.The wavelength of the laser is consistent with the fluorescence spectrum of the upconversion nanomaterials.4.Finally,the fabrication process of microsphere resonators has been introduced,based on which the experimental progress of an upconversion laser is explained.The weekness of the experiment is demonstrated,including the future work.