Thermal effects in kilowatt all-fiber MOPA

Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China.
Optics Express (Impact Factor: 3.49). 08/2011; 19(16):15162-72. DOI: 10.1364/OE.19.015162
Source: PubMed


Thermal effects and output power characteristics of kilowatt all-fiber master-oscillator power amplifier (MOPA) are investigated. Proper designs for cooling apparatus are proposed and demonstrated experimentally, for the purpose of minimizing splice heating which is critical for the reliability of high power operation. By using these optimized methods, a thermal damage-free, highly efficient ytterbium-doped double-clad fiber MOPA operating at 1080 nm with 1.17 kW output was obtained. The maximum surface temperature at the pump light launching end splice of the booster amplifier was 345 K, and the temperature rise for this key splice was 0.052 K/W.

38 Reads
  • Source
    • "It results in difficulties in coupling, especially in the case where it is necessary to launch pulse with high energy or peak power into the fiber. Actually, if we use the near-IR pump source to pump very short fiber to generate SC covering mid-IR, the launched pulse energy or peak power had better be as high as possible, and therefore the delicate microstructure in the pump facet of fiber is subject to damage [6]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Though soft glass such as tellurite or chalcogenide glass is transparent in the range of 3-6 μm, fiber made of it is difficult to generate supercontinuum (SC) to that range because of the high loss, the wavelength limit of pump source, and the challenges in light-coupling. To circumvent these problems, we developed SC light source by using tellurite bulk glass through filamentation. For this scheme, the optical path length in the glass is very short due to the adopted high pump power, so the negative influence of material loss is reduced greatly. The light-coupling is straightforward, and the coupling efficiency is high. The bulk glass for SC generation is cheap, and can be fabricated easily. We adopted a pump wavelength of 1600 nm which is comparatively long. Such a long pump wavelength ensures a large energy ratio of the glass's bandgap to the incident photon, so the disadvantage of small bandgap of tellurite glass is reduced, and the twophoton absorption is avoided as well. We have shown that under suitable pump condition, the SC generation by filamentation can cover from visible to 6 μm. It is the broadest SC generation by tellurite (including glass and fiber). For the suitable pump condition, the glass was free of optical breakdown. If the interface reflections were deducted, the SC conversion efficiency was 87%. The SC conversion efficiency was stable. To the best of our knowledge, this is the first report on filamentation in tellurite glass which has a comparatively small bandgap.
    Proceedings of SPIE - The International Society for Optical Engineering 03/2013; DOI:10.1117/12.2001734 · 0.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The recent research progress of coherent beam combining of high power fiber lasers is reviewed. Key technologies like coherently combinable fiber laser, phase control of multiple beams and beam tilling are specially analyzed. Prospects for single coherently combinable high power fiber amplifier, beam tilling and target-in-the-loop control for propagation in real atmosphere are presented.
    Science China Technological Sciences 07/2013; 56(7). DOI:10.1007/s11431-013-5260-z · 1.19 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Numerous achievements have been made recently by researchers in the areas of fiber laser beam combining and power scaling. Industry has demonstrated multi-kW power from a single fiber amplifier, and a US national laboratory has coherently combined eight fiber amplifiers totaling 4 kW. This paper will survey the recent literature and then focus on fiber laser results from the Laser Division, Directed Energy Directorate of the Air Force Research Laboratory (AFRL). Progress has been made in the power scaling of narrow-linewidth fiber amplifiers, and we are transitioning lessons learned from PCF power scaling into monolithic architectures. SBS suppression has been achieved using a variety of techniques to lower the Brillioun gain, including acoustically tailored fiber, laser gain competition resulting from multitone seeding and inducing a longitudinal thermal gradient. We recently demonstrated a 32-channel coherent beam combination result using AFRL's phaselocking technique and are focused on exploring the limitations of this technique including linewidth broadening, kW-induced phase nonlinearities and auto-tuning methods for large channel counts. Additionally, we have recently refurbished our High Energy Laser Joint Technology Office-sponsored 16-amplifier fiber testbed to meet strict PER, spatial drift, power stability and beam quality requirements.
    Proceedings of SPIE - The International Society for Optical Engineering 02/2012; 8237:27-. DOI:10.1117/12.912154 · 0.20 Impact Factor
Show more


38 Reads
Available from