Lai, C.-C.C.-C.LaiKe, C.-P.C.-P.KeLiu, S.-K.S.-K.LiuJheng, D.-Y.D.-Y.JhengWang, D.-J.D.-J.WangChen, M.-Y.M.-Y.ChenLi, Y.-S.Y.-S.LiYeh, P.S.P.S.YehSHENG-LUNG HUANG2018-09-102018-09-10201101469592http://www.scopus.com/inward/record.url?eid=2-s2.0-79952840080&partnerID=MN8TOARShttp://scholars.lib.ntu.edu.tw/handle/123456789/364915A significant advancement of cw lasing in Cr4+:Y 3Al5O12 (Cr4+:YAG) double-clad crystal fiber grown by the codrawing laser-heated pedestal growth technique was demonstrated at RT. The optical-to-optical slope efficiency of 33.9% is the highest, to the best of our knowledge, among all Cr4+:YAG lasers, whether they are in bulk or fiber forms. The low-threshold lasing of 78:2mW and high efficiency are in good agreement with the simulation. The keys to the high laser efficiency are twofold: one is the improved Cr4+ emission cross section and fluorescence lifetime due to release of the strain on the distorted Cr4+ tetrahedron, which also mitigates photobleaching in Cr 4+:YAG; the other is the improved core uniformity at long fiber lengths. In addition, because of the low threshold, the impact of excited state absorption of the pump light is significantly reduced. The effects of crystal-orientation, self-selected, and pumpdependent linear polarization states were also addressed. © 2011 Optical Society of America.Crystal fiber; Crystal fiber laser; Cw lasing; Double-clad; Emission cross section; Excited state absorption; Fluorescence lifetimes; High efficiency; Laser efficiency; Laser heated pedestal growth; Linear polarization; Long fiber; Low thresholds; Low-threshold lasing; Pump light; Slope efficiencies; YAG; YAG laser; Crystal whiskers; Excited states; Fiber lasers; Fibers; Photobleaching; Crystal orientationjournal article10.1364/OL.36.000784