| Light field manipulation technology is use of optical device materials,structures,physical effects,etc.,the spatial distribution of the optical field or the shape of the laser pulse,pulse width,coherence characteristics of the tuning and manipulation,to achieve a special spatial distribution,or high energy,ultra-fast pulse.The micro-knot resonator(MKR)confines light within a submicron-scale MKR with all-fiber,high-Q characteristics,which improves the intensity of light-matter interaction compared to ordinary straight-through micro-nano fiber.In this paper,the two-dimensional(2D)material is compounded with a MKR,and the special molecular structure,saturable absorption,and strong optical nonlinear coefficient of the 2D material are used to enhance the optical field manipulation characteristics of the MKR,which is used in fiber laser mode manipulation and fiber sensing.The main research of the thesis is as follows.Chapter 1 introduces the research background and significance of MKR,describes the current research status of MKR,and reviews the applications of MKR in fiber lasers and fiber sensors.The basic theory of transmission of micro-nano fiber and MKR is studied,and the characteristic parameters of MKR are introduced to provide theoretical guidance for the fabrication of MKR.Chapter 2 presents a new method of compounding 2D materials with MKR.The new transfer method is based on the special 2D planar structure of the MKR and the surface tension property of the liquid.The method can transfer a 2D material film with uniform and controllable thickness and smooth and flat surface on the inner side of the MKR.MKR with embedded graphene oxide film and MKR with embedded molybdenum disulfide film were prepared using the double-ended method,and then the proposed new method.The MKR with composite 2D materials have better structural stability,larger extinction ratio,and stronger optical nonlinearity.Chapter 3 a high coherence mode-locked fiber laser and a single-wavelength tunable fiber laser based on a MKR with embedded graphene oxide film(GO-MKR)are investigated.Based on the saturable absorption characteristics and filtering characteristics of GO-MKR,the pulse characteristics of the laser are tuned to achieve a mode-locked laser output with low self-starting pumping threshold,high coherence and high stability.A single-wavelength tunable fiber laser with high coherence has been built using GO-MKR’s ability to modulate optical field dispersion and mode selection.Chapter 4 presents a new MKR: the dual-ring MKR(DR-MKR).By introducing a torsion operation into the preparation process of a single-ring MKR,it is self-wound into two ring cavity structures.DR-MKR,in addition to the high Q and strong abrupt field characteristics of MKR,also has high stability and high interference immunity due to its self-wound structure,which can be used for sensors of biological macromolecules and solution ion concentration.In this paper,the operating principle of the DR-MKR is analyzed using the transfer matrix to obtain the transfer function and equivalent cavity length of the dual-ring micro-ring resonator.Then a highly sensitive temperature sensor is built based on the cascaded DR-MKR.Finally,a single-wavelength/dual-wavelength switchable fiber laser with high stability is constructed by using the mode selection property of DRMKR. |
PDF Full Text Request