报告人

Michael Radunsky

单位

报告时间

2015年7月8日

14:30

报告地点

引力中心三楼会议室

报告题目

New Advances in the Photonics Front End of AMO Physics

报告内容

摘 要

Optical atomic spectroscopy and cold atom physics now form the heart of a number of record-breaking physical environments, measurements, and devices including the world’s most sensitive gravitometer, magnetometer, and accelerometer as well as the coldest regions in the universe.  In all these systems, the lasers must exhibit frequency stability as well as agility, while maintaining a narrow linewidth and tunability at the appropriate wavelength.  This performance is dependent not just on the laser itself, but also the control electronics.  As these experiments transition from lab to field, researchers and engineers are demanding ever-more simple, small, and reliable high-performance laser systems.  Vescent Photonics has consistently been a leader in simplifying and shrinking these systems, while simultaneously improving performance and reliability.  I will review the state of the art in lasers, control electronics, and electro-optic modules essential for the front end of cutting edge AMO science and engineering.

报告人

简 介

Michael received his Ph.D. in Physical Chemistry form the University of California at Berkeley.  Over the years, he has worked in a number of laser companies to design, build, and market lasers as diverse as Q-switched Nd:YAGs to ultrafast amplifiers to Quantum Cascade to External Cavity and DBR diode lasers.  He joined Vescent Photonics in 2012 as Director of Sales & Marketing because of the dynamic & fast-paced environment where new, disruptive products are continually released.

报告人

周新

单位

中国科学院大学

报告时间

2015年7月8日

16:30

报告地点

引力中心三楼会议室

报告题目

Earthquake cycle characteristics for the subduction zone of Tohoku, Japan revealed from the geodetic measurements

报告内容

摘 要

An earthquake cycle, including interseismic, coseismic and postseismic processes, is controlled by stress evolution of the fault which enables us to estimate the recurrence interval of a large earthquake. To better understand an earthquake cycle, we have to address some issues related to slip deficit, seismic wave propagation, slow slip, aseismic creep and the earth’s rheology. On the one hand, geodetic techniques such as GPS, InSAR provide a great chance to detect those geophysical signals which can reveal a whole earthquake cycle process with a high precision. In the recent 10 years, coseismic and postseismic gravity changes due to a megathrust event were detected from space-borne gravimetric satellite (GRACE), e.g. the 2004 Sumatra (Mw 9.3), the 2010 Chile (Mw 8.8), and the 2011 Tohoku-Oki (Mw 9.0). On the other hand, the earthquake cycle can be modeled using the dislocation theory. Based upon the dislocation model, the slip history of the fault can be inverted from geodetic observations. In this talk, I focus on the seismic cycle of the Tohoku subduction zone using the geodetic data. The relationship among the interseismic coupling, coseismic slip and afterslip of the 2011 Tohoku event is obtained using GPS and ocean bottom GPS time series. Our results indicate that the viscoelastic relaxation effect which can be modeled by a bi-viscosity structure plays important role in the postseismic deformation. Coseismic slip and afterslip only have a limited overlap as the viscoelastic relaxation is considered. However, the coseismic slip occurred at the region which was locked during interseismic stage. Additionally, we propose a spatial sampling method to invert the coseismic slip for the 2011 Tohoku earthquake using GRACE data; and we obtain the rupture process of this event using high-rate (1 Hz) GPS waveform.

报告人

简 介

BS, Surveying and mapping engineering, School of Geodesy and Geomatics, Wuhan University,2001-2005;

MS, Disaster prevention and reduction engineering and protective engineering, Institute of Seismology, China Earthquake Administration, 2005 - 2008;

PhD, Geophysics, College of Earth Science, University of Chinese Academy of Sciences,September 2010 – July 2013;

Visiting scholar, Department of Geophysics, University of Milan, Italy, Feb. 2012 – July 2012.