502 Watt, Single Transverse Mode, Narrow Linewidth, Bidirectionally Pumped Yb-Doped Fiber Amplifier

Optics Express (Impact Factor: 3.49). 01/2008; 15(25):17044-50. DOI: 10.1364/OE.15.017044
Source: PubMed


High power operation of narrow linewidth optical fiber amplifiers is usually limited by the onset of stimulated Brillouin scattering. In this paper, we present results demonstrating over 500 Watts of power in a single mode beam from a fiber designed to suppress stimulated Brillouin scattering through a reduction in the overlap of the optical and acoustic fields. Simulations demonstrate the potential for this fiber to achieve greater than 1000 Watts of output power. (C) 2007 Optical Society of America.

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Available from: Ming-Jun Li, Dec 26, 2013
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    • "[1] [2], SBS is analyzed using the coupled mode theory and a simple formula for calculating the SBS threshold is derived. In Refs.[3] [4], laser fibers with an increased SBS thresholds using Al/Ge co-doping were proposed and experimentally demonstrated. A similar design by other workers [5] has claimed up to an 11 dB increase in SBS threshold compared to a reference fiber with the same optical effective area. "
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    ABSTRACT: Ge-doped laser fibers with suppressed SBS are proposed. By taking advantage of the difference between optical and acoustic properties, higher SBS thresholds of 3-5 dB are shown numerically while maintaining diffraction limited beam quality.
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    • "This modeling result is verified by the 402 W output without the onset of SBS. The model has also been used to design the fiber amplifiers achieving more than 500 W output [28]. In this case, the model successfully computed thresholds of two fiber amplifiers. "
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    ABSTRACT: A universal model capable of handling various operating conditions has been developed for designing of high power single frequency fiber amplifiers. The model analyzes the impacts of pump configurations, fiber lengths, and fiber temperatures on amplifier performance. It shows that counter-pumped amplifiers are capable of generating several times more output than co-pumped amplifiers. To fully take their advantages and deliver the laser output, a delivery fiber should be properly designed to avoid unwanted SBS which can significantly undermine the amplifier performance. On the other hand, for applications requiring delivery fiber at relative low power, the co-pumped amplifier can be an alternative since it can use the gain fiber as the delivery fiber and thus eliminate requiring an additional delivery fiber. The model also analyzes possible approaches for suppressing SBS, such as applying additional heating, the use of SBS suppressing fiber, and increasing core diameter. It shows that applying additional heating to a co-pumped amplifier can increase the output by a factor of 1.7. Finally, the model concludes that a single frequency amplifier can achieve multiple kilowatts output by carefully choosing amplifier design and utilizing SBS suppression technique.
    Journal of Lightwave Technology 07/2009; 27(13):2189-2198. DOI:10.1109/JLT.2008.2005427 · 2.97 Impact Factor
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    • "Attaining such high powers in a singlefrequency output is much more challenging, because the SBS gain of a single-frequency signal is considerably higher. Nevertheless , other clever solutions have been developed, which, in conjunction with an LMA fiber, have produced high-power single-frequency outputs, including SBS thermal broadening (500 W of output power) [4], and acoustic antiguiding fibers (502 W) [3]. This last scheme is believed to be capable of ultimately producing up to ∼1 kW of single-frequency output power [3]. "
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    ABSTRACT: We report on the development of novel high-power light sources utilizing a Yb<sup>3+</sup>-doped phosphate fiber as the gain element. This host presents several key benefits over silica, particularly much higher Yb<sub>2</sub> O<sub>3</sub> concentrations (up to 26 wt%), a 50% weaker stimulated Brillouin scattering (SBS) gain cross section, and the absence of observable photodarkening even at high population inversion. These properties result in a greatly increased SBS threshold compared to silica fibers, and therefore, potentially much higher output powers out of either a multimode large mode area or a single-mode fiber, which means in the latter case a higher beam quality. To quantify these predictions, we show through numerical simulations that double-clad phosphate fibers should produce as much as ~ 700 W of single-frequency output power in a step index, single-mode core. As a step in this direction, we report a short phosphate fiber amplifier doped with 12 wt% Yb<sub>2</sub> O<sub>3</sub> that emits 16 W of single-frequency single-mode output. We also describe a single-mode phosphate fiber laser with a maximum output power of 57 W. The laser slope efficiency is currently limited by the fairly high fiber loss ( ~ 3 dB/m). Measurements indicate that 77% of this loss originates from impurity absorption, and the rest from scattering.
    IEEE Journal of Selected Topics in Quantum Electronics 02/2009; 15(1-15):93 - 102. DOI:10.1109/JSTQE.2008.2010263 · 2.83 Impact Factor
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