Generation of high-energy soliton-like pulses in 1.9–2.5 µm spectral domain

Vladislav V Dvoyrin,Sergei K Turitsyn

doi:10.1088/2515-7647/abb585

Abstract

We experimentally demonstrate the generation of soliton-like pulses with 195–230 fs duration and energy up to 20 nJ in the spectral region of 1.9–2.5 µm directly from the Tm-doped all-fiber MOPA laser. The emerged Raman solitons generated directly in the fiber amplifier exhibit unusual dynamics and spectral properties forming a supercontinuum without conventional gaps between Stokes pulses. Namely, at the output powers above 2 W, in addition to conventional soliton spectral peaks beyond 2.3 μm, we observe high spectral density over an extended range of 1.95–2.23 μm corresponding to a coherent structure that to the best of our knowledge differs from any previously observed supercontinuum regimes. The average optical power of the fiber laser is at the 3-W level, whereas the estimated peak power reached the 80-kW level. Such a relatively simple laser system with high spectral density is a promising light source for various applications ranging from advanced comb spectroscopy to ultra-fast photonics.

Highlights

Conventional optical fibers have anomalous dispersion at wavelengths higher than approximately 1.3 μm
The emerged Raman solitons generated directly in the fiber amplifier exhibit unusual the author(s) and the title dynamics and spectral properties forming a supercontinuum without conventional gaps between of the work, journal citation and DOI
The part of the total energy stored in the primary Raman soliton started to decrease after the formation of the second one

Summary

Introduction

Conventional optical fibers have anomalous dispersion at wavelengths higher than approximately 1.3 μm. Nonlinear propagation of light in fiber waveguides in the main order is governed by the nonlinear Schrödinger equation (NLSE) [1], which in the case of the anomalous dispersion has well-known solutions in the form of localized coherent pulses—solitons Powerful enough initial waveforms of arbitrary shape (including CW radiation, as an ultimate case) during propagation down the fiber tend to transform, eventually, into soliton or set of solitons [1,2,3]. In the case of the normal fiber dispersion it is possible to generate dissipative solitons References therein) that can offer higher pulse energies compared to conventional solitons. In the red part of the spectrum (longer wavelengths), use of the normal dispersion in fibers is technically challenging

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Discussion

Conclusion