【作者】 周思思；

【导师】 张朴；

【作者基本信息】 华中科技大学 ， 光学， 2021， 硕士

【摘要】 量子通信、量子密码学、光芯片等量子技术的提出推动了纳米结构中单光子实验技术的发展,各种量子技术实现的关键在于对单光子源辐射的有效调控,从而让量子辐射体能够稳定、高效率以及高方向性地耦合到单光子传输通道中。在本论文中,我们借助等离激元纳米光腔和光学微腔来调控量子辐射体的辐射特性及其与片上光波导的耦合特性,在大幅提高量子辐射体辐射速率的同时,在不同的等离激元纳腔-介质微腔混合光腔中,分别实现了量子辐射体与片上光波导的手性耦合和单向高效率耦合。在量子辐射体与片上光波导手性耦合的研究中,我们创新性的利用等离激元纳米光腔调控线偏辐射体的发光特性,在可见光波段将线偏辐射的单量子辐射体调控为圆偏辐射,并将单量子辐射体-纳腔复合系统作为圆偏光源与光波导圆偏局域光场相互作用,实现了线偏量子辐射体与片上直波导及环形腔的手性耦合。在单量子辐射体-纳腔复合系统与环形腔耦合的研究中,当环形腔尺寸比较大时,通常受到计算机内存和计算时间的限制而难以全波仿真计算,我们提出了“一次耦合”的方法来近似计算纳米光腔与环形腔的耦合,为探究多尺度、大尺寸、高Q值混合结构的光学性质提供了新思路。在量子辐射体与片上光波导的单向高效率耦合研究中,金纳米棒二聚体与一端连有波导的氮化硅光子晶体纳米梁微腔耦合,形成等离激元纳腔-光子晶体微腔混合光腔,置于金纳米棒间隙中的量子辐射体与混合光腔“类介质光学微腔”模式耦合,在实现辐射速率提高超过7000倍的同时获得了超过92%的波导耦合效率,为研制高亮度高效率片上集成单光子源提供了重要思路。考虑到实验验证,为了使耦合到片上光波导的能量能被探测器高效率探测,我们还给出了与波导相连的弯曲光栅耦合器的优化设计。更多还原

【Abstract】 The proposal of quantum communication,quantum cryptography,optical chip and other quantum technologies promoted the development of single-photon experimental technology in nanostructures.The key to various quantum technologies lies in the effective control of single-photon source radiation,enabling the quantum emitter to couple to single photon transmission channel with stability,high efficiency and high directionality.In this thesis,we use plasmonic nanocavity and optical microcavity to manipulate the radiation properties of quantum emitters and coupling characteristics of emission to the on-chip optical waveguide.Our design dramatically increases the quantum emitter’s radiation rate,correspondingly,ob-taining chiral coupling and unidirectional high efficiency coupling between quantum emitter and on-chip waveguide respectively in two different plasmonic nanocavity-photonic micro-cavity hybrid systems.In the study of unidirectional high-efficiency coupling between the quantum emitter and the on-chip optical waveguide,we creatively use plasmonic nanocavity to manipulate the luminescence characteristics of single quantum emitter and succeed in converting lin-ear polarized emitter radiation into the far-field circular polarized radiation in the visible light range.Futher,the emitter-nanocavity hybrid system,taken as a circular polarized light source,interacts with local circular field of nanophotonic devices and successfully achieves chiral coupling with on-chip straight waveguide and ring cavity,respectively.In the plas-monic nanocavity-ring cavity hybrid system,it is challenging for the ring cavity of a large scale to perform full-wave simulations due to computer memory and calculation time limited.Thus,we propose a ”one-time coupling” method to estimate the coupling efficiency between the nanocavity and the ring cavity,which provides a new approach for exploring the hybrid structure’s optical properties with multiscale,relatively large scale and high quality factors.In the study of unidirectional high-efficiency coupling between the quantum emitter and the on-chip optical waveguide,an Au nanorod dimer coupling to a silicon nitride photonic crystal nanobeam cavity with a collecting waveguide forms plasmonic nanocavity-photonic crystal microcavity hybrid systems.A quantum emitter,where is inserted in the gap formed by the nanorods and the nanobeam,couples to microcavity-like hybrid mode.Our numeri-cal calculations demonstrate that the enhancement of the spontaneous emission rate reaches up to more than 7000 -folds.Simultaneously,the corresponding collection efficiency into a dielectric waveguide remains more than 92%.The proposed mechanism paves the way towards the development of ultra-bright and high efficiency on-chip integrated single pho-ton sources.Considering the experimental validation,the optimal design of the bent grating coupler connected to the waveguide is given for the efficient collection of light by a detector.更多还原