Tuning And Application Of High-Q Microresonators

With exponential developing of mondem science and technology,the researchers have conducted broad and in-depth studies of quantum mechanics,from theory to prac-tical application.Due to the quantum superposition,quantum non-locality,and no-cloning theorem of quantum states,the quantum information science has developed rapidly around this century,especially quantum communication which theoretically guarantees absolute security of communication,and quantum computers which can pro-vided quantum supremacy over classical computers.Therefore,the quantum informa-tion science has been actively and extensively researched and explored by domestic and foreign researchers.Among them,the dielectric optical microcavities based on the total reflection of light in the medium,which have extremely small light volum and ultru-high photon lifetime,is an important platforms for studying the quantum electro-dynamics and nonlinear optics.Not only in the field of quantum information,but also in the tradtional fields such as sensing and lasers,the microcavities have broad applica-tion and important research value.Inaddition,there are many application such as optical filters,optical circulators,optical delay devices,optical wavelength conversion,opti-cal non-reciprocal devices,and so on.The wavelength conversion of the optical mode based on the microcavity mechanical mode could be used as a conversion node in the future optomechanical quantum network,and can realize the processing and transmis-sion of quantum information effectively.And the synchronization of remote all-optical mechanical modes of microcavity via communication band laser is also of great use in future Micro-Macro entanglement and quantum information networks.This thesis introduced the research work of our lab about the tuning of whispering gallery modes microcavity.In various applications of microcavities in quantum infor-mation science,for example,the matching of the frequencies between atoms and the cavity modes in the cavity quantum electrodynamics,the requirement for on-chip in-tegrated lasers at different wavelengths and filtering or isolating specific wavelengths,tuning of the whispering gallery mode microcavity is essential.But due to the limi-tations of the processing methods of the microcavities,the desired working frequency and actual frequency are often different after the completion of a cavity fabracation,so all of these put forward certain requirements on the tuning technique of the whispering gallery mode microcavities.Therefore,the main work during my doctoral period was to conduct experimental studies on the tuning of the microcavities.And combining the tunable properties of the samples prepared in the laboratory we realized practical optical device.Finally we utilized the tunability of the microcavity and for the first time,all-optical synchronization of two long-distance cascaded microcavity systems is achieved.The specific content of this thesis is as the following four aspects:1.Whispering gallery mode microcavity and tuningThe microcavity coupling system is the basis of our experiment.First of all,we would introduce the basic elements of the WGM microcavity systems,that is the mi-crocavity and the waveguides,as well as the traditional methods of fabracation.Then we would introduce the experiment setup and the basic theory of the corresponding coupling system.A brief introduction to the research on the tuning of the WGM micro-cavities that have already been carried out,as well as the significance and motivation of the tuning of microcavity.2.The fabracation and tuning application of bottle-like microcavityOur main work focus on the tuning and application of whispering gallery mode mi-crocavities.For the first time,I have built the fabracation system for bottle-like micro-cavity in our laboratory,and based on previous work we have made some innovations,and the typical bottle like microcavity with an optical quality factor higher than 108 and convenient for wide-range tuning have been realized.While studying the tuning of op-tical mode,we also studied in-depth the tuning of the mechanical modes of the bottle like microcavities,which has a direct application in the subsequent long-distance all-optical synchronization experiments.Then tunable Raman lasers and tunable add-drop filters based on BLMRs are introduced.3.Long distance all-optical synchronization of cascaded microcavitiesIn recent years,synchronization and frequency locking have been observed by re-searchers in many systems,and they have important applications in signal processing,radio frequency communication,clock synchronization,and phase locking.Therefore,synchronization is a very meaningful research topics.In this part,we would intro-duce all-optical long-distance synchronization between different microcavity systems through an ultra-long-distance(10km)communication band fiber,what is based on the tunable characteristics of the mechanical mode and the optical mode of the bottle like microcavity,the experimental results were analyzed and explained meanwhile.The cas-cade synchronization of the microcavities has broad application prospects in complex optomechanical microcavity networks.4.Polymer microcavity and weak force measurementWe also have carried out some research on the wide tuning of polymer microcavity,and realized the broad-range(50nm)tunable polymer whispering gallery mode micro-cavity.Then we studied the tuning characteristics of its optical mode,and analyzed the feasibility of the polymer microcavity on weak forces measurement.