Q-switched all-fiber cladding-pumped ytterbium-doped fiber lasers

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Abstract A Q-Switched All-Fiber Cladding-Pumped Ytterbium-Doped Fiber Lasers using an acoustic-optic waveguide Q-switched (AOW-Q) with a pigtail fiber are studied. For AOW Q-switched , Ti-diffused YX-lithium niobate substrate was applied as optical waveguide, a SiO 2 /In 2 O 3 film of thickness ~150nm as acoustic waveguide and an acoustic aperture of width 110 µm , in conjunction with N=9 finger pairs. Keywords: Double-clad fiber lasers, Q-Switched All-Fiber Ytterbium-Doped Fiber Lasers , an acoustic-optic waveguide Q-switched. 1. INTRODUCTION Double-clad rare-earth doped fiber lasers pumped by high brightness laser diodes are very efficient and compact sources of cw and pulsed radiation.[1]-[3]. The combination of multi-millijoule pulse energies, high peak power, high spatial beam quality, and a compact cavity arrangement without any active cooling devices makes Q-switched double-clad fiber (DCF) laser very attractive alternative to comparable solid st ate laser for pulsed laser app lications, such as optical time domain reflectometer, range finding, ,rem ote sensing , laser surgical, laser marking and machining, nonlinear frequency conversion, etc. In recent years, some Q-switched DCF have been developed to achieve high energy, high peak power, and short pulse emission [4],[5]. Exploiting distributed back scattering in the fiber as a passive Q-switched mechanism can generate short pulses and high peak power from a DCF Laser[6]. Unlike the conventional Q-switched fiber laser, the pulse width does not depend on the cavity lifetime but rather on the dynamics of stimulated Brillouin scattering (SBS). The SBS provides strong feedback to the laser cavity in the form of a short SBS relaxation oscillation pulse, which is equivalent to an increase of the cavity’s Q factor during a short period of time and leads to a giant pulse generating. However, the pulse repetition rate is not stable. The combin ation of an active Q-switched and SBS can stabilize and tune the repetition rate of the pulses [7]. However, it is still a pa ssive Q-switched mechanism to generate short pulses and high peak power from the fiber laser. Using an electro-optic Q- switched (EO-Q) or acoustooptic Q-switched (AOQ) inserted in DCF cavity, high peak power pulses can be obtained. However, the structure of the Q-switched DCF laser is complex, and its adjustment is very difficult. In this paper, we describe Q-switched All-fiber cladding-pumped Ytterbium-doped fiber lasers using an acoustic-optic waveguide modulator (AOWM) with a pigtail fiber. For AOW Q-switched , Ti-diffused YX-lithium niobate substrate was applied as optical waveguide, a SiO