Ultra-high-Q Microresonator with Applications towards Single Nanoparticle Sensing

Whispering-gallery mode microcavities confines light and enables enhanced light-matter interaction. They are great platforms for enhanced light-matter interactions. Using ultra-high-Q microtoroids and focusing on a phenomenon called mode splitting, we demonstrate the theory and experiments for real-time and label-free detection and size measurement of individual nanoparticles and viruses, with a theoretical size limit of R\u3c10 nm. It enables us to cover a large range of virus and nanoparticle sizes of great interest for biomedicine, nanotechnology, and environmental science. Moreover, this approach allows to identify the components of homogenous mixtures of particles. It exceeds the capabilities of existing schemes with its unique single particle resolution and ability for quantitative size measurement of individual nanoparticles. The techniques described here also pave the way for using active lasing microresonators as particle sensors, in which mode splitting serves as the origin of the radio frequency beatnote in the laser which indicates the binding of nanoparticles. It also lays a solid ground for using microresonators for bio-molecule detection. In addition, two non-spectrogram gased nanoparticle detection techniques: fiber taper detection and resonator reflection mode detection are demonstrated and future implementation on bimolecular detections are discussed

三角对话中的斯特拉霍夫及其批评思想

Based on the primary sources including letters and articles, this paper analyzes the interactive relationship between Strakhov and Dostoevsky, and points out their disagreement. Then Tolstoy is introduced to be compared with Strakhov’s and Dostoevsky’s ideas. Lastly, Strakhov’s revolutionary significance in literary criticism’s paradigm is discusse

Higher Education as a Common Good in China: A Case Study for Ideas and Practices

China began its modern system of higher education with the establishment of the former Peking University in Beijing in 1898. The traditional Confucian philosophy of education has been replaced dramatically by modern western philosophy. However, since the communist party came to power in 1949, the philosophy of higher education has experienced much more dramatic changes. In Mao’s time between 1949 and 1976, Maoism philosophy largely displaced Western, so-called capitalistic, philosophy and dominated Chinese higher education for almost 30 years

Scatterer induced mode splitting in poly(dimethylsiloxane) coated microresonators

We investigate scatterer induced mode splitting in a composite microtoroidal resonator (Q ~ 10^6) fabricated by coating a silica microtoroid (Q ~ 10^7) with a thin poly(dimethylsiloxane) layer. We show that the two split modes in both coated and uncoated silica microtoroids respond in the same way to the changes in the environmental temperature. This provides a self-referencing scheme which is robust to temperature perturbations. Together with the versatile functionalities of polymer materials, mode splitting in polymer and polymer coated microresonators offers an attractive sensing platform that is robust to thermal noise.Comment: 9 pages, 3 figures, 15 reference

Community Reconstruction after the 2008 Sichuan Earthquake: A Reflection on Participatory Development Theories

The participation of China’s civil society in the 2008 Sichuan Earthquake reconstruction featured a number of NGOs and social work organizations. Additionally, participatory development theories were broadly accepted and applied in their community efforts. However, our three-year field work effort in an earthquake-stricken village finds that those theories, based as they are on the presumption of alienated traditional communities, are being confronted with great challenges. Applying the extended case method, we claim that, quite contrary to a single and closed self-recovery, community reconstruction is deeply embedded in and reshaped by a series of much broader social processes: state-dominated post-disaster reconstruction, urban-rural integration development, and social management measures. We further recognize three major forces constructing those social processes: neo-authoritarian local governments, victims with rising citizenship awareness, and community-based NGOs. Redefining the power structure in community reconstruction, we argue that, instead of the traditional bottom-up empowerment approach, in open communities pluralistic governance, through the collaboration of governments, residents, and NGOs, can work more effectively to empower communities and reach sustainable development

Observation and characterization of mode splitting in microsphere resonators in aquatic environment

Whispering gallery mode (WGM) optical resonators utilizing resonance shift (RS) and mode splitting (MS) techniques have emerged as highly sensitive platforms for label-free detection of nano-scale objects. RS method has been demonstrated in various resonators in air and liquid. MS in microsphere resonators has not been achieved in aqueous environment up to date, despite its demonstration in microtoroid resonators. Here, we demonstrate scatterer-induced MS of WGMs in microsphere resonators in water. We determine the size range of particles that induces MS in a microsphere in water as a function of resonator mode volume and quality factor. The results are confirmed by the experimental observations.Comment: 4 Pages, 5 Figures, 13 Reference

Estimation of Purcell factor from mode-splitting spectra in an optical microcavity

We investigate scattering process in an ultra-high-Q optical microcavity coupled to subwavelength scatterers by introducing "splitting quality" Qsp, a dimensionless parameter defined as the ratio of the scatterer-induced mode splitting to the total loss of the coupled system. A simple relation is introduced to directly estimate the Purcell factor from single-shot measurement of transmission spectrum of scatterer-coupled cavity. Experiments with polystyrene (PS) and gold (Au) nanoparticles, Erbium ions and Influenza A virions show that Purcell-factor-enhanced preferential funneling of scattering into the cavity mode takes place regardless of the scatterer type. Experimentally determined highest Qsp for single PS and Au nanoparticles are 9.4 and 16.19 corresponding to Purcell factors with lower bounds of 353 and 1049, respectively. The highest observed Qsp was 31.2 for an ensemble of Au particles. These values are the highest Qsp and Purcell factors reported up to date.Comment: 5 Pages, 4 Figures, 12 Reference