On-Chip Modulation Of Quantum Light Sources At Room Temperature Based On Surface Plasmon Polaritons

With the evolution of artificial intelligence,there is an increasing demand for high computing power,which has severely challenged the supply of global chips and accelerated the development of integrated photonic chips,especially quantum photonics.Compared to electrons,photons can hold a higher capacity of information,perform faster transmission speed,and have great potential in all-optical quantum information processing with high fidelity.Tunable quantum light sources are required for diverse and compatibiable quantum components on chip.However,the integrated quantum light sources based on solid-state quantum emitters(QEs)have limited access to the intrinsic properties of photons,such as polarization states which enable multifunctionality and scalability in advanced photonic quantum technologies.Recently,optical metasurfaces with ultrathin meta-atoms have been widely explored due to their unprecedented capabilities of molding both classical and non-classical lights.However,it is nontrivial to integrate optical metasurfaces with solid-state quantum light sources in a compact manner.In this dissertation,based on the metal-dielectric interface that can support guided surface plasmon polaritons(SPP)modes with strong lateral confinement and the stability of color center in nanodiamonds at room temperature,we have studied on-chip integration and modulation of QE combined with metasurfaces,enabling the direct monolithic integration for compact quantum devices.We have analyzed and optimized the designed device in terms of theory and performance,which improves the compatibility of fabrication process,squeezed the size of the device,and enriched the functionality for quantum light sources.This dissertation has mainly studied the following three aspects:(1)To realize on-chip modulation of polarization states based on quantum light source,hydrogen sesquisiloxane(HSQ)that is a dielectric resist is patterned and covers the metallic Ag substrate.Then,the vertical dipole component in nitrogen vacancy(NV)color center can excite the in-plane radial SPP component.We proposed a quantum hybrid plasmonic nanocircuits(QHPC)with a star-shaped branched waveguide structure,which can convert SPP into photons and radiate into free space with different polarization states.The SPP is effectively confined and propagates within the HSQ waveguide based on transverse magnetic(TM)mode.The propagation length of SPP reaches 6?7.5?m to satisfy the requirements of on-chip active module.By mounting couplers with different polarization states at the end of the QHPC for 6 independent transmission channels,the in-plane SPP can be converted into photons with specific and spatially separated polarization states(H,D,A,R and L)in free space.Herein,the multiple channels provide beam splitting and transmission for the coupled energy from QE while the polarized photons are realized.(2)To modulate the angular momentum of quantum light source on chip,based on the in-plane radial SPP component excited by the vertical dipole component of NV center,the propagation phase of SPP is accumulated with an additional phase factor through the HSQ archimedean spiral gratings,which subsequently couples out spatially separated single photons into free space.The phase variation along azimuthal angle leads to the modulation of spin orbital momentum(SAM)and orbital angular momentum(OAM).The experimentally measured second-order correlations of single NV center before(g~2(0)(28)0.17)and after(g~2(0)(28)0.22)integrating the spiral gratings demonstrate an obvious feature of single-photon streaming.Exciting and tracing the photon counts of the OAM device without any operation and calibration indicates that the single-photon emission is stable for at least 20 mins.By projecting the OAM beam,the mode purities of the OAM topological charges for the corresponding SAM components are measured to be 66.6%and 62.0%,respectively.Besides,the projection measurement also shows the entanglement between the SAM and OAM states.(3)For enhancing the spontaneous emission of in-plane channel on chip,a circular bragg cavity based on HSQ/air gratings is proposed,which ultilizes the SPP radial component excited by the vertical dipole component of germanium vacancy(Ge V)center with a narrow bandwidth at 602 nm of zero phonon line(ZPL)at room temperature.Compared to the straight bragg cavity,the circular bragg cavity possesses a stronger emission enhancement for SPP channel.Due to a synthetic effect of the electromagnetic parameters of the experimental materials,the resonant frequency of the bragg cavity is unpredictably shifted.Therefore,the broad spectrums of NV centers are characterized to calibrate the grating period in the experiment.By adjusting the overall device size,the bragg period is obtained to enhance the ZPL of Ge V center.The measured fluorescence lifetimes before and after integrating the bragg cavity are 9.8 ns and 1.8 ns,respectively,which leads to a 5.5-fold enhancement of spontaneous emission rate.In summary,since the proposed compact quantum devices based on SPP can confine the excitation and modulation of quantum light source within the plane,they greatly reduce the size,improve the compactness,as well as avoid the dependence on external quantum light sources and free-space optical components.The quantum devices based on SPP provide efficient on-demand quantum light sources for the integrated interconnection,and have great potential in developing a high-density and high-capacity platform for quantum information processing on chip.