Molybdenum tungsten disulphide (MoWS₂) as a saturable absorber for a passively Q-switched thulium/holmium-codoped fibre laser

ABSTRACT

In this work, a passively Q-switched Thulium/Holmium-doped fibre laser (THDFL) using a molybdenum tungsten disulphide (MoWS₂) saturable absorber (SA) is proposed and demonstrated. The MoWS₂ nanosheets are prepared by hydrothermal exfoliation and then suspended in a polyvinyl alcohol (PVA) thin film host. Q-switching of the THDFL at a maximum 1550 nm pump power of 445.2 mW gives a maximum repetition rate and minimum pulse width of 36.3 kHz and 2.8 µs with a corresponding pulse energy of 86.4 nJ and peak power of 31.1 mW. The MoWS₂ based Q-switched THDFL's output has a very high signal-to-noise value of ∼62.2 dB which strongly indicates that the laser is working in a stable operation. To the best of our knowledge, this is the first demonstration of MoWS₂ as a passive SA in a THDFL for operation in the 2.0 µm region. The proposed laser would have significant medical and sensing applications, particularly at the biologically active 2.0–2.1 µm regions.

KEYWORDS:

• Saturable absorber
• transition metal dichalcogenides
• Q-switching
• thulium/holmium-doped fibre

Additional information

Funding

Funding for this research was provided for by the Ministry of Higher Education, Malaysia (MOHE) under the grants LRGS (2015)/NGOD/UM/KPT and GA 010–2014 (ULUNG) as well as the Universiti Malaya under the grant RU 013-2018 and PRC HiCoE Second Phase Funding.