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400 µJ 79 ns amplified pulses from a Q-switched fiber laser using an Yb^3+-doped fiber saturable absorber

Optics Express (Impact Factor: 3.49). 10/2012; 20(21):23778-89. DOI: 10.1364/OE.20.023778
Source: PubMed

ABSTRACT We report a passively Q-switched all-fiber laser using a large mode area (LMA) Yb3+-doped fiber cladding-pumped at 915 nm and an unpumped single-mode Yb3+-doped fiber as the saturable absorber (SA). The saturable absorber fiber and gain fiber were coupled with a free-space telescope to optimize the coupling efficiency between the disparate fibers, preferentially bleaching the SA fiber before gain depletion in the pumped fiber. Using this scheme we first demonstrate a Q-switched oscillator with 40 μJ 79 ns pulses at 1026 nm, and show that pulses can be generated from 1020 nm to 1040 nm. The associated peak power of the oscillator alone is more than two orders of magnitude larger than that reported in previous experimental studies using an Yb3+-doped fiber as a saturable absorber. We further demonstrate an amplified pulse energy of 0.4 mJ using an Yb3+-doped cladding pumped fiber amplifier. Experimental studies in which the saturable absorber length, pump times, and wavelengths are independently varied reveal the impact of these parameters on laser performance.

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    • "The laser produces temporal stable pulses with a pulse duration of 140 ns and a pulse energy of 141 J, which is more than 3 times higher than what has been reported in [11]. The peak power reached $1 kW which is twice as high as that reported in [11]. The average power of 14 W at 100 kHz is also sufficiently high to make this laser a stand-alone unit for certain material processing. "
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    ABSTRACT: We demonstrated a passively Q-switched Yb-doped fiber laser in an all-fiber configuration that used a piece of a Yb-doped fiber with a smaller core than the gain fiber as a saturable absorber. The laser generated stable output pulses at 1064 nm with a narrow line width of less than 0.2 nm. The Q-switched pulses have a pulse width of 140 ns and pulse energy of 141 �J at a repetition rate of 100 kHz. The peak power of �1 kW and high slope efficiency of 51% were obtained. The repetition rate of this laser can be varied from a few kHz to 100 kHz with a potential of reaching up to 250 kHz. Stimulated Raman scattering was observed, though at 70 dB below the laser emission. The estimated stimulated Raman threshold is 6.2 kW, which allows this laser to further scale up the power. Because of its high peak power and adequate average power, the laser can be used as a stand-alone module for some applications in material processing. It can be also used as a seed laser for further power amplification.
    IEEE Photonics Journal 06/2014; Vol. 6(No. 3):1501207. · 2.33 Impact Factor
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    • "The laser produces temporal stable pulses with a pulse duration of 140 ns and a pulse energy of 141 J, which is more than 3 times higher than what has been reported in [11]. The peak power reached $1 kW which is twice as high as that reported in [11]. The average power of 14 W at 100 kHz is also sufficiently high to make this laser a stand-alone unit for certain material processing. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrated a passively Q-switched Yb-doped fiber laser in an all-fiber configuration that used a piece of a Yb-doped fiber with a smaller core than the gain fiber as a saturable absorber. The laser generated stable output pulses at 1064 nm with a narrow line width of less than 0.2 nm. The Q-switched pulses have a pulse width of 140 ns and pulse energy of 141 $muhbox{J}$ at a repetition rate of 100 kHz. The peak power of $sim$1 kW and high slope efficiency of 51% were obtained. The repetition rate of this laser can be varied from a few kHz to 100 kHz with a potential of reaching up to 250 kHz. Stimulated Raman scattering was observed, though at 70 dB below the laser emission. The estimated stimulated Raman threshold is 6.2 kW, which allows this laser to further scale up the power. Because of its high peak power and adequate average power, the laser can be used as a stand-alone module for some applications in material processing. It can be also used as a seed laser for further power amplification.
    IEEE Photonics Journal 06/2014; 6(3):1-7. DOI:10.1109/JPHOT.2014.2320745 · 2.33 Impact Factor
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    ABSTRACT: We demonstrate an all-fiber passively Q-switched Yb-doped laser using a piece of Sm-doped fiber as a saturable absorber. The laser was pumped by two 25W, 975 nm fiber coupled diodes and Q-switching was initiated when the ASE generated in the core of the gain fiber bleached the Sm-doped saturable absorber. The laser produced 1064 nm pulses with 28 μJ pulse energy and a 200 ns pulse width at a repetition rate of 100 kHz. The pulse energy and peak power are an order of magnitude higher than what previous reported which was also in all-fiber configuration. Effects of laser parameters, such as Sm-fiber length, pump power and duration on laser performance were presented and discussed. Stable Q-switched pulses were obtained at the repetition rate varying from 10 kHz to 100 kHz, which makes this laser suitable for different applications.
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