Unidirectional light emission in a deformed circular-side triangular microresonator.

A waveguide-connected deformed circular-side triangular microresonator is proposed and fabricated. Room temperature unidirectional light emission is experimentally demonstrated in the far-field pattern with a divergence angle of 38°. Single mode lasing at 1545.4 nm is realized at an injection current of 12 mA. The emission pattern changes drastically upon the binding of a nanoparticle with radius down to several nanometers, predicting applications in electrically pumped, cost-effective, portable and highly sensitive far-field detection of nanoparticles.

Comparison of single- and dual-mode lasing states of a hybrid-cavity laser under optical feedback.

In this Letter, we design and realize a hybrid-cavity laser with single- or dual-mode lasing states and study the nonlinear states of the laser under external optical feedback (EOF). The laser at a dual-mode state easily and directly enters the chaotic state without periodic oscillation states and display chaos for a much wider range of the EOF magnitude than the laser at a single-mode state. A flat chaotic signal is obtained for the laser at a dual-mode lasing state under a weak EOF benefitting from the low-frequency energy enhancement caused by mode competition between the dual modes.

Unidirectional emission and nanoparticle detection in a deformed circular square resonator.

We propose a novel deformed square resonator which has four asymmetric circular sides. Photons leak out from specific points, depending on the interplay between stable islands and unstable manifolds in phase space. By carefully breaking the mirror reflection symmetry, optical modes with strong chirality approaching 1 and unidirectional emission can be achieved simultaneously. Upon binding of a nanoparticle, the far-field emission pattern of the deformed microcavity changes drastically. Due to the EP point of the degenerate mode pairs in the deformed cavity, chirality-based far-field detection of nanoparticles with ultra-small size can be realized.

Mode control through anti-Hermitian coupling in regular-polygonal microcavities with non-uniform gain and loss.

We theoretically and numerically study optical modes in regular-polygonal microcavities with non-uniform gain and loss, where high quality (Q) whispering-gallery-like modes typically appear as superscar states. High Q superscar modes can be described by the propagating plane waves in an effective rectangle formed by unfolding the periodic orbits and exhibit regular and predictable spatial field distributions and transverse-mode spectra. With non-uniform gain and loss, anti-Hermitian coupling between the transverse modes with close frequencies occurs according to the mode coupling theory, which results in novel mode properties such as modified mode spectra and field patterns, and the appearance of exceptional points. Numerical simulation results are in good agreement with the theoretical analyses, and such analyses are also suitable for other kinds of high Q microcavities with non-uniform gain and loss. These results will be highly useful for studying non-Hermitian physics in optical microcavities and advancing the practical applications of microcavity devices.

[Investigation on the internalization pathway of microparticles into human umbilical cord endothelial cells].

OBJECTIVE: To investigate the mechanisms underlying the incorporation of microparticles(MP) derived from human bone marrow mesenchymal stem cells (MSCs) into human umbilical cord endothelial cells (HUVECs). METHODS: MPs were isolated from the supernatants of MSCs which had exposed to a hypoxia/serum-deprivation condition. Electron microscope was used to identify the MPs. The surface molecule profile was evaluated with the bead-based flow cytometry technique. The expression level of the phosphatidylserine receptor (PSR) was detected by immunofluorescence cytochemistry. MPs were co-cultured with HUVECs in the presence or absence PSR-antibody, and the internalization of MPs was observed with laser scanning microscopy. RESULTS: The MPs derived from MSCs expressed highly PS, while PSR expressed on the surface of HUVECs. The confocal result revealed that MPs could quickly be uptaken by the endothelial cells, and mainly distributed in the cytoplasm surrounding of the nuclei. The internalization of MPs reduced significantly after PSR specific blockage. CONCLUSION: The reaction between PS on the MP and the PSR of HUVECs plays an important role in the internalization of MSC-MPs.