Tunable Q-switched thulium-doped Fiber Laser using multiwall carbon nanotube and Fabry-Perot Etalon filter

Abstract

In this paper, we demonstrate an electro-tunable Thulium-doped Fiber Laser (TDFL) using a voltage-controlled Fabry-Perot Etalon (FPE) filter with passive Q-switching capability, obtained by using a multi-walled carbon-nanotube (MWCNT) thin-film as a saturable absorber (SA). To the best of our knowledge, this is the first demonstration of a wavelength-tunable Q-switched TDFL using an FPE filter. The tunable TDFL has a wavelength-tuning range of 41.95nm, from 1965.40nm up to 2007.35nm. Q-switching operation starts at a pump power of 94.72mW and destabilizes at a maximum input pump power of 146.39mW. By varying the pump power, the repetition rate and the pulse width can be tuned with a maximum tuning range of 15.5kHz and 7.0µs respectively. The laser also has a maximum pulse energy of 82.6nJ and a peak power of 27.52mW. The use of the MWCNT thin-film as an SA generates a stable Q-switching operation, which is verified by its relatively high signal-to-noise ratio at a value of 55.0dB.