Generating 3000W nanosecond laser of all-fiber structure by using high power pulsed fiber combiner

15 mJ and high-peak-power nanosecond pulse based on all-fiber MOPA system

“…As delineated in [22], the maximum attainable pulse energy from the amplifier is approximately ten times the ASElimited saturation energy. Given the saturation fluence of Yb 3+ at 0.5 μJ/μm 2 [23], the theoretical upper limit for extractable pulse energy from a 100-μm-core amplifier resides around 17 mJ, which is congruent with analogous experimental findings detailed in [6]. It is pertinent to consider the mode-field diameter of the fundamental mode, which approximates a radius of 33 μm as estimated through Marcuse's equation [24].…”

“…In recent years, the pursuit of laser systems combining high-average power and pulse energy has led to studies involving larger core diameter fibers in the main amplifier stage. However, nonlinear effects, particularly Stimulated Raman Scattering (SRS), continue to impact fiber laser output, especially in industrial high-pulsed lasers [2,5,6]. The SRS effect causes nonlinear wavelength shifting when signal power exceeds the SRS threshold [7][8][9].…”

“…Employing a 300 μm LMA Yb-doped fiber in the main amplifier yielded an average power of 512 W, 51.2 mJ pulse energy, and 72% slope efficiency [2]. For further laser power improvements, multistage amplifiers [20], large-pitch photonic crystal fibers (LPFs) [10], beam combining by more laser modules [6] was investigated, resulting in 36 mJ at 10-ns pulse width, 26mJ at 60-ns pulse width, and 50 mJ at 150-ns pulse width, respectively. It is important to note that nonlinear effects, pump coupler capacity, LMA fiber manufacturing complexities, and other factors limit average power and pulse energy improvements in all-fiber laser systems.…”