Scaling of average power in sub-MW peak power Yb-doped tapered fiber picosecond pulse amplifiers

Abstract

Prospects for average power scaling of sub-MW output peak power picosecond fiber lasers by utilization of a Yb-doped tapered fiber at the final amplification stage were studied. In this paper, it was shown experimentally that a tapered fiber allows the achievement of an average power level of 150 W (limited by the available pump power) with a peak power of 0.74 MW for 22 ps pulses with no signs of transverse mode instability. Measurements of the mode content using the S2 technique showed a negligible level of high order modes (less than 0.3%) in the output radiation even for the maximum output power level. Our reliability tests predict no thermal issues during long-term operation (105 hours) of the developed tapered fiber laser up to kilowatt output average power levels.

Tapered Multicore Fiber for High-Power Laser Amplifiers

“…Thus, it has been shown that it is possible to amplify the out-of-phase mode in a tapered multicore amplifier to a value of the total peak power that significantly exceeds the self-focusing threshold. We note that close to 1 MW peak powers were demonstrated experimentally in a single-core tapered fiber without Raman instability and a small contribution of the ASE [15], [16], so power scaling to multi-megawatt level in tapered MCFs looks feasible.…”

“…These parameters are in principle achievable using existing fiber manufacturing technologies. The fabrication of such optical fibers does not present much difficulty, since the proven technology of drawing a tapered optical fiber from a solid standard preform [16] will make it possible to fabricate a tapered multicore fiber with the length of tapered section of the order of 0.5-1 meter from a corresponding multicore preform in the same way.…”

“…The possibility of creating a completely monolithic amplifier and laser with a fiberized injection of pump radiation into the tapered fiber is demonstrated [18]. Peak powers of a megawatt level are demonstrated [14], [15], [16], [17], which are comparable in order of magnitude with the self-focusing limit in silica. At this, up to several tens of MW after compression is shown [15], [19] when using chirped pulse amplification.…”

“…A specific feature of tapered fibers is the relative simplicity of the structure of their cores (in fact, the step-index profile can be used) and the possibility of a completely monolithic structure, as well as the simplicity of implementing a structure with a double cladding for injection of pump radiation [9]. High-power laser systems of the kilowatt level [10] with good beam quality [11], [12], high energy Q-switched pulsed lasers [13] and ultrashort pulse amplifiers [14], [15], [16], [17] are demonstrated using tapered fibers. The possibility of creating a completely monolithic amplifier and laser with a fiberized injection of pump radiation into the tapered fiber is demonstrated [18].…”

Towards Ultimate High-Power Scaling: Coherent Beam Combining of Fiber Lasers

“…There are several reports on utilizing T-DCFs to simultaneously achieve the high peak and average power pulses in picosecond ranges with excellent beam quality, which have resulted in a few hundred watts in average power and megawatts level in peak power via T-DCF [222]. For example, in 2020, a laser with the 1.26 MW peak power and 200 W average output power was obtained via implementing the T-DCF, without the need for additional stretching techniques [223].…”