Yong Yang

In this work, we theoretically and experimentally investigate the optomechanical transduction mechanism in a system of two coupled microresonators under different coupling scenarios, categorized into electromagnetically induced transparency, intermediate, and Autler–Townes splitting regimes. We show that interference between the dispersion and dissipation channels gives rise to an asymmetric line shape in the optomechanical spectrum. These effects are experimentally demonstrated using a fiber taper-coupled whispering gallery resonator system consisting of a microbubble resonator and a micropendulum. Finally, we conduct a comprehensive analysis of the optical forces between the microbubble and the micropendulum and propose that an experimentally feasible trapping scheme is achievable, even in the presence of strong optomechanical interference.

An effective method, reducing the material volume of the air cavity by asymmetrical tapering fiber, is demonstrated to enhance the sensitivity of the strain sensor dramatically. High-sensitive strain sensors are fabricated through this method that splicing and tapering fiber with arc discharge at the misaligned center of the air cavity. The strain sensitivity of the sensor is measured to be ~ 41.81 pm/μ at a resonant wavelength ~ 1560 nm ranging from 0 to 500. In addition, the experimental results show that the asymmetrical tapered-fiber enables both the material volume to smaller and the wall thickness to thinner, resulting in strain sensitivity higher. The proposed sensors have the advantages of fabricated repeatability, high sensitivity, and compact size, benefiting its practical sensing applications.

In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady-state transmission spectrum through the coupling waveguide. Alternatively, sensing based on cavity ring-up spectroscopy, i.e. CRUS, can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh Q-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which may improve the data collection rate.

In this work, we show that the application of a sol-gel coating renders a microbubble whispering gallery resonator into an active device. During the fabrication of the resonator, a thin layer of erbium-doped sol-gel is applied to a tapered microcapillary, then a microbubble with a wall thickness of 1.3 μm is formed with the rare earth ions diffused into its wall. The doped microbubble is pumped at 980 nm and lases in the emission band of the Er³⁺ ions at 1535 nm. The laser wavelength can be shifted by aerostatic pressure tuning of the whispering gallery modes of the microbubble. Up to 240 pm tuning is observed with 2 bar of applied pressure. We also show that the doped microbubble could be used as a compact, tunable laser source.

In this letter, a packaged add-drop filter composed of a silica microsphere resonator with a diameter of $80~\mu \text{m}$ and an optical microfiber coupler with a waist diameter of 1 $\mu \text{m}$ is investigated. A one-step fabrication process using UV curable epoxy is shown to stabilize the coupling between the microsphere and the microfiber coupler, which is used for the add and drop ports. The packaged microsphere-microfiber coupler device has a high $Q$ -factor of $1\times 10^{7}$ in the add–drop filter configuration. This device has excellent features, such as improved ease of fabrication, multiple resonant peaks, and high mechanical stability.

In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady state transmission spectrum through the coupling waveguide. Alternatively, cavity ring-up spectroscopy (CRUS) sensing can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh \textit{Q}-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which might improve the data collection rate.