Speaker: Dr. GAO Guojun, Karlsruhe Institute of Technology (KIT, Germany)
Time: 15:00, December 12, 2017 (Tuesday)
Venue: Conference Room, R & D Center of High Power Laser Components
Guojun Gao got the Doctor degree of engineering from University of Jena (Germany) in 2013. Currently, he is a post-doctor researcher in Karlsruhe Institute of Technology (KIT, Germany). His research focuses on novel multi-dimensional opto-electronic materials: chemical designs, novel synthesis approaches, structure-properties relations, and their photonic applications. He has published 30 SCI-indexed papers 23 as first or corresponding author). The total citation time is > 600; the citation without self-citation is > 550, H-index is 17. He got Chinese Government Self-financed Oversea Student Award in 2012. He is regular reviewer for wide range of SCI-indexed journals including: Chem. Soc. Rev., Inorg. Chem., Nanoscale, Opt. Lett., Opt. Express, Opt. Mate. Express, J. Am. Ceram. Soc., etc. More than 20 referee reports are written every year.
Finely tuned up-conversion (UC) emission colors while maintaining high UC emission efficiency are important for many applications, e.g., photonic markers, anticounterfeiting, plastic recycling, etc. Firstly, finely tuned NIR-to-visible La2O3:Yb,Re (Re = Er, Ho and Tm) UC materials with high UC quantum yield (UCQY) will be presented. The UC emission colors of La2O3:Yb,Er from green to reddish-orange while maintaining the high UCQY can be precisely tailored. La2O3:Yb,Ho and La2O3:Yb,Tm respectively yield efficient pure green and NIR (at ~800 nm) UC emission with UCQY equivalent to that of La2O3:Yb,Er. Secondly, Yb3+/Nd3+ co-doped La2O3 microcrystal thermometer upon excitation of 980 nm laser diode (LD) as a potential candidate for NIR ratio-metric thermometer will be presented. The combined features of suitable energy gap (ΔE) value of 950 cm-1, weak thermal quenching effect and high peak emission maximum temperature (833 K), high relative sensitivity (SR) of 1334/T2, excellent repeatability of FIR, and impressively low temperature uncertain ∆Tmin of 0.1 K make them promising as non-contact NIR ratio-metric thermometers over a wide temperature range up to 1233 K.