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Strong coupling between solid-state quantum emitters and microcavities paves the way for optical coherent manipulation of quantum state and provides opportunities for quantum information processing. However, it is still a challenge to realize strong coupling due to the spectral and spatial mismatch between quantum emitters and cavity modes. Here, we propose a scheme to tune the coupling between a single QD and a microdisk with 1D photonic crystal nanobeam cavity. Based on Finite-Difference Time-Domain (FDTD) method and Green's function expression for the evolution operator, we demonstrate that QDs with emission wavelengths +1.27 nm and -1.44 nm detuned from the bare microdisk mode can be coupled to the system strongly. Particularly, we observe simultaneous coupling between QD and two cavity supermodes, which enriches the optical coherent control methods of quantum states. By adjusting the distance between the two cavities, we can control the coupling between QD and photons. Furthermore, benefiting from the natural integration of nanobeam cavity to waveguide, such a system provides advantages for implementing quantum internet.

Monolayer transition metal dichalcogenides (TMDs) are ideal materials for atomically thin, flexible optoelectronic and catalytic devices. However, their optoelectrical performance such as quantum yield and carrier mobility often shows below theoretical expectations due to the existence of defects. For monolayer TMD-based devices, finding a low-cost, time-efficient, and nondestructive technique to visualize the change of defect distribution in the space domain and the defect-induced change of the carrier’s lifetime is vital for optimizing their optoelectronic properties. Here, we propose a microscopic pump-probe technique to map the defect distribution of monolayer TMDs. It is found that there is a linear relationship between transient differential reflection intensity and defect density, suggesting that this technique not only realizes the visualization of the defect distribution but also achieves the quantitative estimation of defect density. Moreover, the carrier lifetime at each point can also be obtained by the technique. The technique used here provides a new route to characterize the defect of monolayer TMDs on the micro-zone, which will hopefully guide the fabrication of high-quality two-dimensional (2D) materials and the promotion of optoelectrical performance.

We observed enhanced energy transfer between quantum dots which were spin coated on the surface of Ag island film. By adjusting the thickness of Al2O3 spacer layer (4-16 nm) between quantum dots and Ag island film, we studied the distance dependence of the plasmon enhanced energy transfer. Experimental results showed the energy transfer efficiency increased as the quantum dots approached closer to the Ag film. A time-correlated single-photon counting system was also applied to study the dynamics of the plasmon enhanced energy transfer between quantum dots. Obvious decay rate increasing was discovered from time-resolve photoluminescence spectra of both the donor and accepter quantum dots, which clearly confirmed the existence of strong photon-exciton interaction. The theoretical analysis performed by the finite difference time domain method and COMSOL program, further revealed large electronic field and energy transfer rate enchantments on the surface of Ag island film, which uncovered the dominant reasons for the quantum dots’ enhanced energy transfer.

We investigate the light emission characteristics for single two level quantum dot (QD) in a realistic photonic crystal (PC) L3 cavity based upon the local coupling strength between the QD and cavity together with the Green's function in which the propagation function related to the position of the detector is taken into account. We find for a PC cavity that the line shape of the propagation function in frequency domain is identical to that of the cavity and independent on the detector's position. We confirm that this identity is not influenced by the horizontal decay of the cavity. Furthermore, it is revealed that the vacuum fluorescence spectrum of the coupled system never give the triplet in strong coupling regime. Our work demonstrates that the experimental spectral-triplet in coupled system of single QD and PC cavity cannot be individually understood by vacuum Rabi splitting without including other physics mechanism.

We present a new approach which allows one to insert a silica nanosphere with a single quantum dot into a high Q photonic crystal slab nanocavity with an asymmetric nanohole in the center. The high Q cavity is optimized by adjusting air holes around the L3-type cavity based on three-dimensional finite-difference time-domain simulation. High Q value of 48 700 in this asymmetric cavity is achieved. The performance of the cavity with an assumed silica sphere containing a single quantum dot in the nanohole is also discussed, in which the Q factor can reach 5×104 and modal volume V is 0.048μm3 (∼0.62(λ0/n)3). It is found that the electric field intensity in the nanohole is much stronger than the maximum electric field in the cavity without a nanohole. This makes it possible to locate the precise position of the quantum dot with respect to the cavity mode electric maximum. This system provides a good candidate for realizing a strong interaction between a quantum dot and cavity for the study of cavity quantum electrodynamics.

This paper proposes a method to design an incident-angle-insensitive polarization-independent polarization rotator. This polarization rotator is composed of layers of impedance-matched anisotropic metamaterial (IMAM) with each layer's optical axes gradually rotating an angle. Numerical simulation based on the generalized 4x4 transfer matrix method is applied, and the results reveal that the IMAM rotator is not only polarization-independent but also insensitive to the angle of incidence. A 90 degrees polarization rotation with tiny ellipticity variation is still available at a wide range of incident angles from 0 to 40 degrees, which is further confirmed with a microwave bi-split-ring resonator (bi-SRR) rotator. This may be valuable for the design of optoelectronic and microwave devices.

We present a detailed theoretical analysis which reveals a useful insight to understand the resonant dissipative behavior of 3D woodpile metallic photonic crystals in the spectral response. We observe that a small amount of structural parameter modifications can induce great flexibility to alter the properties of the absorption resonance with even an extremely narrow band width of ~13 nm. Analyzing the dispersive properties of the 3D woodpile metallic photonic crystals and performing thorough numerical simulations for the finite number of layers we found that the magnitude, band width, and tunability of enhanced absorption can be easily optimized, which can be of significance to design an efficient photonic crystal thermal emitter.