CC BY
16The 30th International Conference on Advanced Laser Technologies
ALT'23
LS-O-1
Xe laser based on hollow-core fiber excited by microwave-discharge
A.V. Gladyshev, D.G. Komissarov, S.M. Nefedov, A.F. Kosolapov, V.V. Velmiskin,
A.P. Mineev, I.A. Bufetov
Prokhorov General Physics Institute of the Russian Academy of Sciences, 38 Vavilov St., Moscow, Russia
The attempts to create gas-discharge fiber lasers started about 15 years ago, shortly after the development of HCFs. The main problem here is the difficulty of maintaining plasma in a thin (about 100 ^m in diameter) core. The HCF diameter of the order of ~100 ^m was used in almost all studies, since it provides an acceptable level of optical losses in a HCF. The most advanced result in this field so far was as follows. It was declared that optical amplification due to stimulated transitions in Xe atoms at wavelengths of 3.11, 3.37, and 3.51 ^m was observed [1]. However, this result has not received further development so far.
In this work, a gas-discharge fiber laser based on a hollow-core fiber has been demonstrated for the first time. To pump it, we used the previously proposed scheme for excitation of a gas discharge in a hollow-core fiber using microwave radiation [2] and the results of microwave discharge stability investigation in noble gases under similar conditions [3].
The design of the gas-discharge fiber laser included a 100-cm-long segment of a revolver-type hollow-core fiber (RF, see Fig. 1b) filled with a He:Ar:Xe gas mixture in a ratio of 100:10:1 and a total pressure of 130 Torr. Both ends of the RF were hermetically sealed into miniature gas cells, which had inlets for gas injection and resonators windows to decouple the radiation. The highly reflective (HR) mirror was a polished aluminum plate. The output mirror with a multilayer interference coating had a high reflectivity (~90%) in a wide wavelength range from 2000 to 3500 nm. A section of the fiber 30 cm long was placed in a pulsed microwave field with a frequency of 2.45 GHz and a strength of about 1 kV/cm. The discharge in RF core was initiated by short-term UV irradiation of RF with a mercury lamp. The MW pulse duration was 20 ^s with a repetition rate of 400 Hz. After alignment of the resonator mirrors, generation was observed at a wavelength of 2.027 ^m. The lasing emission spectrum was monitored using band-pass filters and a Yokogawa 625 spectrum analyzer (see Fig. 2). Fig. 1a shows oscillograms of a MW pump pulse (curve 1), an oscillogram of a laser pulse obtained using a photodetector sensitive in the spectral range from 1 to 5 ^m (curve 2). Curve 3 was obtained under conditions identical to curve 2, but with a misaligned HR mirror. The maximum peak generation power was ~1 mW.
Fig.1. a) Oscillograms of MW pump pulse and Xe laser output at different^. , „ . ... „. .
,, .. <-5 , ,„r ,■ ■ . Fig.2. Spectrum of Xe gas discharge fiber laser.
conditions; b) cross-section of the revolver HCF used in experiments.
This research was supported by Russian Science Foundation (grant No. 22-19-00542), https://rscf.ru/pro-ject/22-19-00542/.
[1] S. A. Bateman, W. Belardi, F. Yu et al. Gain from Helium-Xenon Discharges in Hollow Optical Fibres at 3 to 3.5 |im," in CLEO: 2014 Postdeadline Paper Digest, OSA Technical Digest (online) (Optica Publishing Group, 2014), paper STh5C.10.
[2] A. Gladyshev, S. Nefedov, A. Kolyadin et al. Microwave Discharge in Hollow Optical Fibers as a Pump for Gas Fiber Lasers, Photonics, vol.9, p.752 (2022).
[3] I. Bufetov, A. Gladyshev, S. Nefedov et al. MW discharge maintaining in the hollow core fibers for gas fiber lasers, Doklady RAS Physics, vol.509, pp. 3-8, (2023) (in Russian).
