Dispersion-Engineered Step-Index Tellurite Fibers for Mid-Infrared Coherent Supercontinuum Generation from 1.5 to 4.5 μm with Sub-Nanojoule Femtosecond Pump Pulses

Paul Froidevaux,Takenobu Suzuki,Kenshiro Nagasaka,Frédéric Désévédavy,Pierre Mathey,Yasutake Ohishi,Frédéric Smektala,Grégory Gadret,Arnaud Lemière,Jean-Charles Jules,Bertrand Kibler

doi:10.3390/app8101875

Abstract

Mid-infrared supercontinuum generation from 1.5 to 4.5 µm with sub-nanojoule femtosecond pump pulses is demonstrated by using a short segment of dispersion-engineered step-index tellurite fiber with very low OH content. Distinct group-velocity dispersion regimes in a simple design of step-index tellurite fiber are also reported, which allows to choose the nonlinear pulse propagation regime according to the required tailoring of the supercontinuum source. Numerical simulations based on the generalized nonlinear Schrödinger equation are used to determine optimized fiber parameters before experimental demonstrations. We also analyse the coherence properties of the resulting supercontinuum sources.

Highlights

Mid-infrared light sources from 2 to 20 μm are of key importance for applications in molecular sensing, medicine, security and defense, and in free-space communication [1]
Allows generation further in the range of fiber core diameter. These numerical studies, we show that coherent mid-IR supercontinuum generation is obtained in our
By combining a fine control of core diameter in such fibers with the recent development of 2-μm fiber lasers, we present an easy way to tailor mid-IR

Summary

Introduction

Mid-infrared (mid-IR) light sources from 2 to 20 μm are of key importance for applications in molecular sensing, medicine, security and defense, and in free-space communication [1]. The mid-IR spectrum covers important atmospheric windows, and numerous features of molecular gases, toxic and explosive agents, water, and pollutants. Coherent and broadband radiations bring numerous practical advantages for some applications such as spectroscopy and frequency metrology, and this can be conveniently obtained by means of fiber-based supercontinuum light generated from femtosecond mode-locked lasers [2,3], surpassing thermal infrared sources and challenging quantum cascade lasers. Recent developments focus on satisfying the user needs for mid-IR SC application such as compact and high repetition rate sources, single-mode behavior, all-fiber systems, high power spectral density, and coherent emission across the SC spectrum [6,7,8,9,10,11]

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Conclusion