CC BY
10The 30th International Conference on Advanced Laser Technologies
LS-I-7
ALT'23
High peak power fiber lasers and its applications
M.E.Likhachev
Prokhorov General Physics Institute of the Russian Academy of Sciences, Dianov Fiber Optics Research Center, 38
Vavilov Street, 119333 Moscow, Russia
likhachev@fo.gpi.ru
In this report current state-of-art for high peak power fiber lasers operated and its applications is presented. Two types of fiber lasers - Yb-doped, operated near 1 ^m and Er-doped operated near 1.55 ^m are discussed. High peak power lasers with picoseconds pulse duration enables rapid and precise energy deposition into a processed material ensuring suppressed thermal diffusion and thus reduced a heat affected zone formation. Moreover, extremely high intensity of the pulses allows volume processing of materials, which are transparent at the wavelength of the pulses, via a nonlinear absorption process: one can utilize a two-photon polymerization and a three-dimensional processing of glasses and polymers to fabricate photonic devices and biochips. Moreover, high pak power fiber lasers are extremely useful for high harmonic generation in order to obtain a radiation in the vacuum ultraviolet wavelength range. The highest peak power could be obtained with Yb-doped fiber lasers. In particular chirped pulse amplifier with a final amplification stage based on a 108 ^m ytterbium-doped core photonics crystal fiber (PCF) was enabling generation of 3.8 GW pulses with a duration of 480 fs and an energy of 2.2 mJ [1]. However, PCF-based systems contain a number of bulk elements and lose main advantages of all-fiber systems, such as compactness, reliability and high quality of an output beam. Thus, a great number of efforts is currently spent for development of alternative fiber design, which allow to built all-fiber high peak power. An alternative design of large-mode-area fibers is the so-called tapered fibers, in which a core diameter increases along the fiber length from a 6-10 ^m (corresponding to single-mode operation) by several times (up to 100 ^m core diameter). Few groups develop tapered Yb-doped fibers and a number of remarkable results (i.e. MW-peak power level directly from the final amplification stage, sub-kW average power and etc) were obtained by these groups [2-6].
Demonstrated output peak power of Er-doped fiber lasers is much lower than that of Yb-doped one. However, such lasers are of great demand as well. First of all, such lasers are used in different lidar applications -amplification spectral range of Er-ions falls into the transparency window of the atmosphere, also very important that 1.5 ^m lasers are concerned to be "eye-safe" type of light sources (contrary to the lasers operated near 1 ^m). Additionally, some applications require development of lasers, operated in a specific wavelength range, which could be covered by Er-doped fiber lasers only. Today the best results in term of peak power and pulse energy were achieved by Yb-free Er-doped fibers pumped through the cladding [7-8]. Even better results were obtained using tapered Er-doped fiber geometry [9]. However, the optimal configuration, which allows one to achieve simultaneously high peak power and a high pump-to-signal conversion efficiency is Yb-free Er-doped double clad fiber followed by Er-Yb large-mode-area fiber [10].
[1] T.Eidam, et al, "Fiber chirped-pulse amplification system emitting 3.8 GW peak power", Optics Express, 19(1), 255-260 (2010).
[2] K.Bobkov, et al, "Sub-MW peak power diffraction-limited chirped-pulse monolithic Yb-doped tapered fiber amplifier", Optics Express, 25(22), 26958-26972 (2017).
[3] V. Filippov, et al, "Highly efficient 750 W tapered double-clad ytterbium fiber laser", Optics Express, 18(12), 12499-12512 (2010).
[4] K.Bobkov et al, "Scaling of average power in sub-MW peak power Yb-doped tapered fiber picosecond pulse amplifiers", Optics Express,29(2), 1722-1735 (2021).
[5] A. Petrov, et al, "Picosecond Yb-doped tapered fiber laser system with 1.26 MW peak power and 200 W average output power", Sci. Rep., 10(1), 17781 (2020).
[6] K.K. Bobkov, et al, "All-fiber chirped-pulse amplifier emitting 670 fs pulses with 92 MW peak power", IEEE Photonics Technology Letters, v34(18), pp.977-980 (2022).
[7] L.Kotov, et al, "Millijoule pulse energy 100-nanosecond Er-doped fiber laser", Opt. Lett., 40(7), p. 1189 (2015).
[8] L.V.Kotov, et al, "Record-peak-power all-fiber single-frequency 1550 nm laser", Laser Phys. Lett., 11(9), p.095102 (2014).
[9] M.M.Khudyakov, et al, "Narrow-Linewidth Diffraction-Limited Tapered Er-Doped Fiber Amplifier with 2 mJ Pulse Energy", Photonics, 9(12), p.933 (2022).
[10] M.M.Khudyakov, et al, "Highly efficient 3.7 kW peak-power single-frequency combined Er/Er-Yb fiber amplifier", Opt. Lett., 45(7), p.1782 (2020).
