Q-Switched Mode-Locking in Er-Doped ZBLAN Fibre Laser Employing Carbon Nanotube Saturable Absorber

In recent years, significant efforts have been devoted to developing compact ultrafast laser sources based on rare-earth-doped fluorozirconate (ZBLAN) fibres [1], operating in the mid-infrared (MIR) spectral range. Among the critical nonlinear materials, saturable absorbers based on single-walled carbon nanotubes (CNTs) have been intensively investigated for the fibre and solid-state laser mode-locking in near-infrared wavelength band [2]. The CNTs band gap and, thus, operation wavelength are defined by the tube diameter and chirality. The operation at a longer wavelength range requires larger tube diameters, which are quite challenging to achieve without introducing various defects. The aerosol (floatingcatalyst) chemical vapour deposition (CVD) method has demonstrated great potential with high productivity and quality of carbon nanotubes even with larger diameters [3].