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Employing nanostructure to generate large chiroptical response has been cultivated as an emerging field, for its great potentials in integrated optics, biochemistry detections, etc. However, the lack of intuitive approaches for analytically describing the chiroptical nanoparticles has discouraged researchers from effectively designing advanced chiroptical structures. In this work, we take the twisted nanorod dimer system as a basic example to provide an analytical approach from the perspective of mode coupling, including far-field coupling and near-field coupling of nanoparticles. Using this approach, we can calculate the expression of circular dichroism (CD) in the twisted nanorod dimer system, which can establish the analytical relationship between the chiroptical response and the basic parameters of this system. Our results show that the CD response can be engineered by modulating the structure parameters, and a high CD response of ∼ 0.78 under the guidance of this approach has been achieved.

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.

Spontaneous emission lifetime distribution in the basic unit cell or on a plane of the excited emitters embedded in woodpile photonics crystals with low refractive index contrast are investigated. It is found that the spontaneous emission lifetime distribution strongly depends on the position and transition frequency of the emitters, and has the same symmetry as that of the unit cell. The lifetimes of emitters near the upper gap edge are longer than that in the center of the pseudo-gap, which is quite a contrast to the conventional concept. Furthermore, it is revealed that the polarization orientation of the emitters has significant influence on the lifetime distribution, and may result in a high anisotropy factor (defined as the difference between the maximum and minimum values of the lifetime) up to 4.2. These results may be supplied in probing the lifetime distribution or orientation-dependent local density of states in future experiments.

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.

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.