Two octaves mid-infrared supercontinuum generation in As₂Se₃ microwires.

Alaa Al-Kadry,Mohammed El Amraoui,Younès Messaddeq,Martin Rochette

doi:10.1364/oe.22.031131

Abstract

We report the first demonstration of mid-infrared supercontinuum generation in As₂Se₃ chalcogenide microwires with the added advantage of using low energy pulses. The generated SC covers two octaves of bandwidth from 1.1 μm to 4.4 μm at -30 dB. This exceeds the broadest reported SC bandwidth in As₂Se₃ microwires by a factor of 3.5. The microwire geometry and pumping conditions are the key parameters in generating the 3.3 μm bandwidth while using a low pump pulse energy of 500 pJ.

Highlights

Supercontinuum (SC) generation in the 2-5 μm wavelength range of the mid-infrared (IR) attracts a lot of attention for applications in diverse fields including optical coherence tomography [1], biomedical technologies [2], and molecular spectroscopy [3]
Mid-IR SC generation in ChG fibers such as As2Se3 and As2S3 is of a special interest due to their wide transparency window [15] and their high nonlinear refractive index (n2) that is up to ∼930 times that of silica [16]
A broadband SC in ChG fibers can be generated by shifting the zero-dispersion wavelength (ZDW) close to the central wavelength of the pump source

Summary

Introduction

Supercontinuum (SC) generation in the 2-5 μm wavelength range of the mid-infrared (IR) attracts a lot of attention for applications in diverse fields including optical coherence tomography [1], biomedical technologies [2], and molecular spectroscopy [3]. Several structures of ChG fibers have been designed including microwires ( called nanowires) [17], microstructured [18] and tapered microstructured [19] fibers Such fiber structures control the waveguide dispersion and increase modal confinement and nonlinearity [20]. Several experimental and theoretical investigations on mid-IR SC generation were reported in ChG microstructured fibers [5, 6, 14, 21,22,23,24] and microwires [25, 26]. For fibers based on As2Se3 (∼4× n2 of As2S3 fiber [28]), SC from 2.1 μm to 3.2 μm was experimentally demonstrated using microstructured fibers [5] pumped with 100 fs pulses at a wavelength of 2.5 μm. The use of relatively long pulses of 800 fs prevents significant changes of their temporal and spectral profile while propagating in the untapered and transition regions of a tapered fiber (see e.g. [32])

Experimental setup

As2Se3 microwire design

Mid-IR SC using pump laser without amplification

Mid-IR SC using amplified pump laser

Conclusion