Title

Supercontinuum Generation from a Thulium Ultrafast Fiber Laser in a High NA Silica Fiber

Document Type

Article

Publication Title

IEEE Photonics Technology Letters

Publication Date

11-15-2019

Abstract

A broadband supercontinuum is generated from a thulium ultrafast soliton fiber laser in a high numerical aperture silica fiber with low nJ seed pulse energies. Amplification of a thulium based ultrafast soliton ring fiber laser in two customized thulium doped fiber amplifiers provides pulses varying in energy between 1.8 nJ and 13.5 nJ. Coupling these seed pulses into a high numerical aperture silica fiber UHNA 7 of varying length, a systematic study of the impact of pulse energy, pulse duration and nonlinear fiber length is conducted. Based on the normal dispersion, self-phase modulation dominates for lower pump power values and results in a symmetric spectral broadening process. For higher pulse energies, four-wave mixing and Raman scattering contribute to a strong red-shift of the spectrum beyond 2.3~\mu \text{m}. For a fiber length of 20 m of UHNA 7, a broadband supercontinuum spanning from 1.7~\mu \text{m} to 2.33~\mu \text{m} is generated with a 20 dB spectral bandwidth of 502 nm with an output pulse energy of 4.4 nJ, corresponding to an output power of 92 mW. This represents a low seed energy threshold for efficient flat supercontinuum generation at infrared wavelengths.

Volume

31

Issue

22

First Page

1787

Last Page

1790

DOI

10.1109/LPT.2019.2946835

ISSN

10411135

E-ISSN

19410174

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