TY - JOUR

T1 - High-energy pulses from all-PM ultra-long Yb-fiber laser mode-locked with quasi-synchronous pumping

AU - Nyushkov, Boris

AU - Ivanenko, Aleksey

AU - Smirnov, Sergey

AU - Kobtsev, Sergey

N1 - Funding Information: This research was supported by Russian Science Foundation under Grant 17-12-01281 . The used simulation software was developed with support from Ministry of Science and Higher Education of the Russian Federation in the frame of the task FSUS-2020-0036 . The developed laser was tested for material microprocessing capability at NSTU Materials Research Center. Publisher Copyright: © 2021 Elsevier Inc.

PY - 2021/10

Y1 - 2021/10

N2 - We explore, for the first time, mode-locking capabilities and frontiers of a quasi-synchronous pumping technique implemented in an all-polarization-maintaining (all-PM) kilometer-long Yb-fiber laser. This technically simple approach to synchronous pumping relies on sine-wave modulation of pump power at a frequency slightly detuned from the laser cavity inter-mode frequency or its multiple. In combination with the scaled-up all-PM-fiber cavity, it has provided stable generation of linearly polarized (scalar) high-energy (up to 130 nJ) pulses with tunable nanosecond duration at the fundamental and harmonic repetition rates ranging from 0.23 to 0.69 MHz. The obtained combination of such a low repetition rate, such a high energy level, and polarization stability is unique for actively mode-locked all-fiber stimulated-emission-based master oscillators. We reveal that detuning of the pump modulation frequency is the key parameter for the pulse shaping control in such mode-locked laser, and further intracavity pulse shortening towards sub-nanosecond duration is theoretically possible with measures preventing pulses from accumulation of excessive nonlinear phase. The demonstrated approach opens up new prospects for pump-modulation-based mode locking in diode-pumped lasers with such inertial active media as rare-earth-doped fibers.

AB - We explore, for the first time, mode-locking capabilities and frontiers of a quasi-synchronous pumping technique implemented in an all-polarization-maintaining (all-PM) kilometer-long Yb-fiber laser. This technically simple approach to synchronous pumping relies on sine-wave modulation of pump power at a frequency slightly detuned from the laser cavity inter-mode frequency or its multiple. In combination with the scaled-up all-PM-fiber cavity, it has provided stable generation of linearly polarized (scalar) high-energy (up to 130 nJ) pulses with tunable nanosecond duration at the fundamental and harmonic repetition rates ranging from 0.23 to 0.69 MHz. The obtained combination of such a low repetition rate, such a high energy level, and polarization stability is unique for actively mode-locked all-fiber stimulated-emission-based master oscillators. We reveal that detuning of the pump modulation frequency is the key parameter for the pulse shaping control in such mode-locked laser, and further intracavity pulse shortening towards sub-nanosecond duration is theoretically possible with measures preventing pulses from accumulation of excessive nonlinear phase. The demonstrated approach opens up new prospects for pump-modulation-based mode locking in diode-pumped lasers with such inertial active media as rare-earth-doped fibers.

KW - Fiber lasers

KW - Laser mode locking

KW - Synchronous pumping

UR - http://www.scopus.com/inward/record.url?scp=85111997635&partnerID=8YFLogxK

U2 - 10.1016/j.yofte.2021.102650

DO - 10.1016/j.yofte.2021.102650

M3 - Article

AN - SCOPUS:85111997635

VL - 66

JO - Optical Fiber Technology

JF - Optical Fiber Technology

SN - 1068-5200

M1 - 102650

ER -