High-Order Resonant Peaks and Polarization Dependence of Microphotoluminescence in Whispering-Gallery Mode ZnO Microrod Cavity

High order phenomena in the visible range and with polarization dependence in the ultraviolet (UV) region of the microphotoluminescence (micro-PL) spectrum in whispering-gallery mode (WGM) ZnO microrod cavity have been thoroughly studied at room temperature. WGM ZnO microrod cavity with good crystallinity is produced by the CVD growth method, and the ZnO microrod structures are characterized by structural and optical methods. Through the micro-PL spectrum measurement of the ZnO microrod, it is found that high-order resonance peaks appeared in the visible region. The different polarization conditions can be adjusted by rotating the angles of the polarizer, and it is proved that the micro-PL spectrum has strong polarization-dependent behavior in the UV region. Our results imply broad application potentials in the study of ZnO microrod-based photonic cavity devices.

A study of the high-inclination population in the Kuiper belt – III. The 4:7 mean-motion resonance

ABSTRACT The high-inclination population in the 4:7 mean-motion resonance (MMR) with Neptune has also substantial eccentricities (e ≳ 0.1), with more inclined objects tending to occupy more eccentric orbits. For this high-order resonance, there are two different resonant modes. The principal one is the eccentricity-type mode, and we find that libration is permissible for orbits with $e\ge e_\mathrm{ c}^0$, where the critical eccentricity $e_\mathrm{ c}^0$ increases as a function of increasing inclination i. Correspondingly, we introduce a limiting curve $e_\mathrm{ c}^0(i)$, which puts constraints on the (e, i) distribution of possible 4:7 resonators. We then perform numerical simulations on the sweep-up capture and long-term stability of the 4:7 MMR, and the results show that the simulated resonators are well constrained by this theoretical limiting curve. The other 4:7 resonant mode is the mixed-(e, i)-type, and we show that stable resonators should exist at i ≳ 20○. We predict that the intrinsic number of these mixed-(e, i)-type resonators may provide a new clue into the Solar system’s evolution, but, so far, only one real object has been observed resonating in this mode.

Damping Force and Loading Position Dependence of Mass Sensitivity of Magnetoelastic Biosensors in Viscous Liquid

We established the vibration governing equation for a magnetoelastic (ME) biosensor with target loading in liquid. Based on the equation, a numerical simulation approach was used to determine the effect of the target loading position and viscous damping coefficient on the node (“blind points”) and mass sensitivity (Sm) of an ME biosensor under different order resonances. The results indicate that viscous damping force causes the specific nodes shift but does not affect the overall variation trend of Sm as the change of target loading position and the effect on Sm gradually reduces when the target approaches to the node. In addition, Sm decreases with the increase of viscous damping coefficient but the tendency becomes weak at high-order resonance. Moreover, the effect of target loading position on Sm decreases with the increase of viscous damping coefficient. Finally, the results provide certain guidance on improving the mass sensitivity of an ME biosensor in liquid by controlling the target loading position.