Generation of tightly compressed solitons with a tunable frequency shift in Raman-free fibers Driben, R. Malomed, B.A. Optimization of the compression of input 𝑁 -solitons into robust ultra-narrow fundamental solitons, with a tunable up- or downshifted frequency, is proposed in photonic crystal fibers free of the Raman effect. Due to the absence of the Raman self-frequency shift, these fundamental solitons continue propagation, maintaining the acquired frequency, once separated from the input 𝑁 soliton’s temporal slot. A universal optimal value of the relative strength of the third-order dispersion is found, providing the strongest compression of the fundamental soliton is found. It depends only on the order of the injected 𝑁 -soliton. The largest compression degree significantly exceeds the analytical prediction supplied by the Satsuma–Yajima formula. The mechanism behind this effect, which remains valid in the presence of the self-steepening, is explained. 2013 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_6501 https://ris.uni-paderborn.de/record/43252 Driben R, Malomed BA. Generation of tightly compressed solitons with a tunable frequency shift in Raman-free fibers. <i>Optics Letters</i>. 2013;38(18):3623-3626. doi:<a href="https://doi.org/10.1364/OL.38.003623">10.1364/OL.38.003623</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1364/OL.38.003623 info:eu-repo/semantics/closedAccess