Statistics of Chaotic Resonances in an Optical Microcavity

Distributions of eigenmodes are widely concerned in both bounded and open systems. In the realm of chaos, counting resonances can characterize the underlying dynamics (regular vs. chaotic), and is often instrumental to identify classical-to-quantum correspondence. Here, we study, both theoretically and experimentally, the statistics of chaotic resonances in an optical microcavity with a mixed phase space of both regular and chaotic dynamics. Information on the number of chaotic modes is extracted by counting regular modes, which couple to the former via dynamical tunneling. The experimental data are in agreement with a known semiclassical prediction for the dependence of the number of chaotic resonances on the number of open channels, while they deviate significantly from a purely random-matrix-theory-based treatment, in general. We ascribe this result to the ballistic decay of the rays, which occurs within Ehrenfest time, and importantly, within the timescale of transient chaos. The present approach may provide a general tool for the statistical analysis of chaotic resonances in open systems.Comment: 5 pages, 5 figures, and a supplemental informatio

Institutional investor network, analyst public information and extreme risks

This paper builds the institutional investor network on the basis of the common stock holdings of mutual funds with large positions. Institutional investors share and interact private information through social networks. Seen from separating private and public information, the effects of private information sharing in institutional investor networks and the effects of public information diffusion on extreme risks are examined, respectively. Then, the integrated impact of institutional investor information sharing with analyst on extreme risks is analysed. Empirical research has found that analyst public information spread will decrease the probability of extreme risks. The information sharing in social network of institutional investors will restrain stock market extreme risks. The closer network of institutional investors lower the influence of analyst public information on extreme risks. In addition, we also found that stock liquidity has weakened the inhibition of fund network information sharing on extreme risks. The research results provide reference for the authorities to regulate market participant behaviours so as to avoid risks

Broadband enhancement of light harvesting in luminescent solar concentrator

Luminescent solar concentrator (LSC) can absorb large-area incident sunlight, then emit luminescence with high quantum efficiency, which finally be collected by a small photovoltaic (PV) system. The light-harvesting area of the PV system is much smaller than that of the LSC system, potentially improving the efficiency and reducing the cost of solar cells. Here, based on Fermi-golden rule, we present a theoretical description of the luminescent process in nanoscale LSCs where the conventional ray-optics model is no longer applicable. As an example calculated with this new model, we demonstrate that a slot waveguide consisting of a nanometer-sized low-index slot region sandwiched by two high-index regions provides a broadband enhancement of light harvesting by the luminescent centers in the slot region. This is because the slot waveguide can (1) greatly enhance the spontaneous emission due to the Purcell effect, (2) dramatically increase the effective absorption cross-section of luminescent centers, and (3) strongly improve the quantum efficiency of luminescent centers. It is found that about 80% solar photons can be ultimately converted to waveguide-coupled luminescent photons even for a low luminescent quantum efficiency of 0.5. This LSC is potential to construct a tandem structure which can absorb nearly full-spectrum solar photons, and also may be of special interest for building integrated nano-PV applications