Study On Directional Emission And Modes Of Optical Microcavity

Whispering-gallery modes optical microcavities can use continuous or complete reflection to localize light in the cavity.Therefore,Whispering gallery mode optical microcavity has the advantages of high-quality factor(Q)and small mode volume(V),which greatly improves the interaction ability of light and matter in the microcavity,and has a considerable number of applications in the fields of quantum communication,nonlinear optics,biological sensing and lasers.However,due to the high rotational symmetry of the whispering gallery mode optical microcavity,it increases the difficulty of light collection and signal acquisition.Therefore,the ability to achieve the directional discharge of lasers is the key to practicality.In order to break the rotational symmetry of the microcavity to achieve directional laser emission,people have designed and studied various deformation cavities.In this paper,a cascade model of the microsphere cavity is designed,which expands the free spectral range(FSR)of the microcavity based on the wiper effect,and then directly connects the waveguide on the microcavity,and selects the position of the appropriate waveguide to connect the microcavity,which not only does not reduce the quality factor of the microcavity,but also effectively inhibits the high-order resonance mode inside the microcavity,and realizes the directional single-mode laser emission of the microcavity.This includes the following:In thesis,combined with the domestic and foreign development of whispering gallery mode optical microcavity,several typical whispering gallery mode microcavities and their applications are introduced.Then,the working principle of the whispering gallery mode optical microcavity is analyzed,including the main parameters affecting the performance of the microcavity,the pattern characteristics in the microcavity,and the principle of microcavity coupling.Secondly,the FDTD Solutions is used for simulation calculations,and the microcavity and the waveguide is obtained by scanning the spacing between the microcavity and the waveguide and the width of the waveguide on the laser directional emission efficiency.In addition,we analyzed the vernier effect between two microcavities of different sizes,designed multiple groups of microcavities of different sizes to achieve vernier effect,and designed two microcavity cascade models with different radii based on the directional laser emission of this single microcavity.The cascaded microcavity has the vernier effect,which expands the free spectral range(FSR)of the microcavity by more than ten times,suppressing high-order resonances while only one spectral peak appears in a wavelength range.The waveguide is directly connected to the beads to achieve the directional discharge of the microcavitral laser in a single-mode emission.Compared with other modes,the quadrilateral mode is more stable and has a higher quality factor(Q).Based on the weak field position of the waveguide connected to the microcavity,the quadrilateral mode is stabilized in the cavity without breaking the loop,and the emission efficiency of the micro-cavity laser along the waveguide is as high as 82%.And take advantage of the single mode advantage of the structure,the sensing test is carried out,and the high sensing sensitivity is finally obtained.Finally,the application of mode splitting in the microring cavity coated with fluorescent high refractive index film is discussed.In summary,this paper takes the whispering gallery mode optical microcavity as the research platform,combined with domestic and foreign research hotspots,proposes a structure coupled with the weak field of the cascaded double microcavity and the waveguide,which realizes the directional discharge of the laser while ensuring the high quality factors.At the same time,due to the low cost of the device,it provides theoretical and applied research and support for microcavitary laser and sensing.