Shien-Kuei Liaw received double doctorate degrees in photonics engineering from National Chiao-Tung University in 1999, and in mechanical engineering from National Taiwan University in 2014, respectively. He joined the Chunghua Telecommunication, Taiwan, in 1993. Since then, he has been working on optics communication and fiber based devices. He was a visiting researcher at Bellcore (now Telcordia), US for six months in 1996 and a visiting Professor at University of Oxford, UK in autumn 2011. Currently, he is a distinguished Professor at National Taiwan University of Science and Technology (NTUST). He has been awarded about 37 patents and has published 240 journal articles and international conference presentations. He has been actively contributing for various conferences as program chair, organizing committee chair, session chair and invited speaker. His research interests are in optical sensing, optical communication, fiber optics and reliability testing. Prof. Liaw is a senior member of IEEE, OSA ans SPIE. rn
In this talk, we will review and discuss Ytterbium doped fiber laser in 1064 nm band. For linear-cavity fiber laser schemes, the elements may base on a loopback optical circulator (OC), a broadband fiber mirror, a Faraday rotator mirror or a 2x2 fiber coupler integrated a partial reflectance fiber Bragg grating (FBG) as the front cavity end. For single-longitudinal mode (SLM) selection, using multiple subring cavities based on the Vernier effect, a piece of gain fiber saturable absorber as modes filter or their hybrid type. For wide-tuning range fiber laser, the wavelength tuning mechanism include the use of a broadband fiber mirror (BFM) integrated tunable FBGs as cavity ends, using a 3-point bending device, using a four-lamina composite device to facilitate wavelength tuning of FBGs, a large tuning range cover 1064 nm band with good resolution of 0.1 nm is obtained. Laser characteristics such as output, signal-to-noise ratio, linewidth, threshold pump power, pumping slope efficiency and side mode suppress ratio are measured. The pumping power efficiency may be improved more than 10% by recycling the residual pump power to the gain medium. With the advantages of simple structure, large pump slope efficiency and short cavity, the Ytterbium doped fiber laser may find potential applications in various ways.
K.A.Trukhanov is doctor of technical science (the radiation and electromagnetic safety at space, 2006). He is the principal researher of Institute of Biomedical Problems RAS. He has published more than 25 papers in reputed journals.
Cherenkov radiation (CHR) occurs when velocities of charged particles in a medium exceed the phase velocity of light in it.rnI. M. Frank (Nobel laureate together with P. A. Cherenkov and I. E. Tamm) once remarked: CHR radiators were the first macroscopic coherent emitters.rnThe report provides a method of finding the velocity distribution of particles (VDP) in accelerator’s beams. VDP is obtained from the solution of the Volterra integral equation of the first kind of the convolution type. The right-hand side of this equation presents a nonlinear part of the experimental dependence of CHR intensity on refractive index magnitudes for the given beam. VDP is the second derivative of this dependence on the inverse value of \"n\". The solution is stable when at taking into account a priori information about its properties.rnThe usage of radiators with an optical dispersion is discussed. The dispersion hampers the use of Cherenkov methods somewhat but here it turns into a \"friendly phenomenon\" which may serve to determine VDP even in single bunch of particles. The possibility of finding VDP with the help of holographic methods for rapid processing of information is discussed. The determination of VDP distribution over the beam cross section is analyzed. The determination of VDP is possible also at a case of beams with non-zero transverse particle velocities. The proposed method is particularly useful when the VDP is narrow which is typical for high energy beams. Essentially the method is non-destructive in most applications.rn