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Multi-kilowatt Single-mode Ytterbium-doped Large-core Fiber Laser
정윤찬,Johan Nilsson,David N. Payne,Alexander J. Boyland,Jayanta K. Sahu,정승환 한국광학회 2009 Current Optics and Photonics Vol.13 No.4
We have demonstrated a highly efficient cladding-pumped ytterbium-doped fiber laser, generating >2.1 kW of continuous-wave output power at 1.1 μm with 74% slope efficiency with respect to launched pump power. The beam quality factor (M2) was better than 1.2. The maximum output power was only limited by available pump power, showing no evidence of roll-over even at the highest output power. We present data on how the beam quality depends on the fiber parameter, based on our current and past fiber laser developments. We also discuss the ultimate power-capability of our fiber in terms of thermal management, Raman nonlinear scattering, and material damage, and estimate it to 10 kW.
이승종,이동영,김현태,Luis A. Vazquez-Zuniga,정윤찬,Jayanta K. Sahu 한국광학회 2013 Current Optics and Photonics Vol.17 No.2
We present a comparative experimental analysis of the thermal spectroscopic characteristics of a phosphosilicate (P)-based ytterbium-doped fiber (YDF) against an aluminosilicate (Al)-based YDF in the temperature range of 25 to 150ºC. We also characterize the fibers as gain media in a cladding-pumped amplifier configuration. While both fibers exhibit comparable trends in their thermal characteristics, there are noticeable distinctions in the fluorescence lifetime reduction rate and the spectral dependence of the transition cross-sections. The P- and Al-based YDFs present thermal lifetime reduction rates of 0.012%/ºC and 0.026%/ºC, respectively. In particular, in the spectral region at ~940 nm, the absorption cross-section of the P-based YDF undergoes significantly less thermal change compared to that of the Al-YDF. In the cladding-pumped amplifier configuration operating at a total gain of 10 dB, the Al-based YDF generally performs betters than the P-based YDF in the temperature range of 25 to 75ºC. However, it is highlighted that in the high temperature range of over 75ºC, the latter shows a less gain reduction rate than the former,thereby yielding higher relative output power by 3.3% for a 1060-nm signal, for example.