逆切伦科夫效应在二氧化硅微球中超短拉曼孤子形成中的作用

Dy$^{3+}$掺杂二氧化硅玻璃微球的黄色受激发射

Yellow stimulated emission from Dy$^{3+}$-doped silica glass microspheres

本研究通过光纤熔接制备Dy³⁺掺杂二氧化硅玻璃回音壁模式微球，表征其形貌与离子分布，经倏逝场泵浦观测到黄色受激发射，为可见光窄线宽光源提供新途径。

Optomechanical Transduction and Characterization of a Silica Microsphere Pendulum via Evanescent Light

Dissipative optomechanics has some advantages in cooling compared to the conventional dispersion dominated systems. Here, we study the optical response of a cantilever-like, silica, microsphere pendulum, evanescently coupled to a fiber taper. In a whispering gallery mode resonator the cavity mode and motion of the pendulum result in both dispersive and dissipative optomechanical interactions. This unique mechanism leads to an experimentally observable, asymmetric response function of the transduction spectrum which can be explained using coupled-mode theory. The optomechanical transduction, an…

可功能化二氧化硅微球涂料中的稳健辐射冷却

Robust Radiative Cooling in Functionalizable Silica Microsphere Paints

本文研究了基于二氧化硅微球的无序涂层在多次散射区域中，微球直径变化对辐射冷却性能的影响，发现当系统处于扩散区时，冷却性能对粒径变化具有稳健性，允许根据表面化学或加工需求选择粒径而不牺牲冷却效果。

Frequency tuning of the whispering gallery modes of silica microspheres for CQED and spectroscopy

We have tuned the whispering gallery modes of a fused silica microresonator over nearly 1 nm at 800 nm, i.e. over 0.5 FSR or 10^6 linewidths of the resonator. This has been achieved by a new method based on the stretching of a two-stem microsphere. The devices described below will permit new Cavity-QED experiments with this high-Q optical resonator when it is desirable to optimize its coupling to emitters with given transition frequencies. The tuning capability demonstrated here is compatible with both UHV and low temperature operation, which should be useful for future experiments with laser …

Filamentation of ultrashort laser pulses in silica glass and KDP crystal: A comparative study

Ionizing 800-nm femtosecond laser pulses propagating in silica glass and in potassium dihydrogen phosphate (KDP) crystal are investigated by means of a unidirectional pulse propagation code. Filamentation in fused silica is compared with the self-channeling of light in KDP accounting for the presence of defect states and electron-hole dynamics. In KDP, laser pulses produce intense filaments with higher clamping intensities up to 200 TW/cm$^2$ and longer plasma channels with electron densities above $10^{16}$ cm$^{-3}$. Despite these differences, the propagation dynamics in silica and KDP are a…

二氧化硅微球中的阴极荧光增强机制

Cathodoluminescence Enhancement Mechanisms in Silica Microspheres

本文通过光谱、角分辨和空间分辨测量分解了二氧化硅微球中阴极荧光的产生与发射机制，证明光子产生发生在球体表面，并发现微球可作为高数值孔径准直透镜，在自由空间实现高质量定向CL，有望推动电子-光子纠缠对和量子发射体CL等新型量子测量。

Surface and internal scattering in microspheres: limits imposed on the Q-factor and mode splitting

Accurate calculation of internal and surface scattering losses in fused silica microspheres is done. We show that in microspheres internal scattering is partly inhibited as compared to losses in the bulk material. We pay attention on the effect of frozen thermodynamical capillary waves on surface roughness. We calculate also the value of mode splitting due to backscattering and other effects of this backscattering.

Flexible daytime radiative cooling enhanced by enabling three-phase composites with scattering interfaces between silica-microspheres and hierarchical porous coatings

Daytime radiative cooling has attracted considerable attention recently due to its tremendous potential for passively exploiting the coldness of deep-sky as clean and renewable energy. Many advanced materials with novel photonic micro-nanostructures have already been developed to enable highly efficient daytime radiative coolers, among which the flexible hierarchical porous coatings (HPCs) are a more distinguished category. However, it is still hard to precisely control the size distribution of the randomized pores within the HPCs, usually resulting in a deficient solar reflection at the near-…

Ultrashort dissipative Raman solitons in Kerr resonators driven with phase-coherent optical pulses

External driving of passive, nonlinear optical resonators has emerged over the past decade as a novel route for the generation of ultrashort optical pulses and corresponding broadband frequency combs. Whilst the pulse formation dynamics in such systems differ dramatically from those manifesting themselves in conventional mode-locked lasers, the demarcation between the two traditionally distinct paradigms has recently begun to blur, with demonstrations of hybrid systems incorporating both external driving and active media shown to offer specific advantages. Here we explore a new pathway for ult…

Mechanical oscillations in lasing microspheres

We investigate the feasibility of activating coherent mechanical oscillations in lasing microspheres by modulating the laser emission at a mechanical eigenfrequency. To this aim, 1.5% Nd3+:Barium-Titanium-Silicate microspheres with diameters around 50 μm were used as high quality factor (Q>10^6) whispering gallery mode lasing cavities. We have implemented a pump-and-probe technique in which the pump laser used to excite the Nd3+ ions is focused on a single microsphere with a microscope objective and a probe laser excites a specific optical mode with the evanescent field of a tapered fibre. The…

Optomechanical light storage in a silica microresonator

Coherent inter-conversion between an optical and a mechanical excitation in an optomechanical resonator can be used for the storage of an optical pulse as an excitation in a mechanical oscillator. This optomechanical light storage is enabled by external writing and readout pulses at one mechanical frequency below the optical resonance. In this paper, we expand an earlier experimental study [Phys. Rev. Lett. 107, 133601 (2011)] on storing an optical pulse as a radial breathing mode in a silica microsphere. We show that the heterodyne beating between a readout pulse and the corresponding retriev…

利用超快小角X射线散射探测二氧化硅薄膜上飞秒激光诱导周期表面结构的形成

Probing the formation of femtosecond laser-induced periodic surface structures on silica films by ultrafast small-angle X-ray scattering

本研究利用超快小角X射线散射实时探测飞秒激光在二氧化硅薄膜上诱导周期表面结构的形成，提出包含纳米散射体与裂纹演化及脉冲间反馈的五阶段模型。

Incubation Induced Light Concentration Beyond the Diffraction Limit for High-Resolution Glass Printing

In the past two decades, tremendous efforts have been exerted to understand and control the delivery of ultrashort laser pulses into various types of transparent materials ranging from glass and crystal to polymer and even bio-materials. This approach opens up the route toward determinative and highly localized modification within the transparent materials, enabling three-dimensional (3D) micromachining of the materials into sophisticated structures and devices with the extreme geometrical flexibility. Owing to the linear diffraction and nonlinear self-focusing effects, the focal volume typica…

High-resolution multimodal flexible coherent Raman endoscope

Coherent Raman scattering microscopy is a fast, label-free and chemically specific imaging technique that has a high potential for future in-vivo optical histology. However, its imaging depth into tissues is limited to the sub-millimeter range by absorption and scattering. Performing coherent Raman imaging in a fiber endoscope system is a crucial step to image deep inside living tissues and provide the information inaccessible with current microscopy tools. However the development of coherent Raman endoscopy has been hampered by several issues in the fiber delivery of the excitation pulses and…