Kelly sideband suppression and wavelength tuning of a conventional soliton in a Tm-doped hybrid mode-locked fiber laser with an all-fiber Lyot filter

Abstract

We demonstrate a stable conventional soliton in a Tm-doped hybrid mode-locked fiber laser by employing a homemade all-fiber Lyot filter (AFLF) and a single-wall carbon nanotube. The AFLF, designed by sandwiching a piece of polarization-maintained fiber (PMF) with two 45° tilted fiber gratings inscribed by a UV laser in PMF with a phase-mask scanning technique, shows large filter depth of ∼9 dB and small insertion loss of ∼0.8 dB. By optimizing the free spectral range of the AFLF, the Kelly sidebands of a conventional soliton centered at 1966.4 nm can be dramatically suppressed without impairing the main shape of the soliton spectrum. It gives the pulse duration of 1.18 ps and bandwidth of 3.8 nm. By adjusting the temperature of the PMF of the AFLF from 7°C to 60°C, wavelength tunable soliton pulses ranging from 1971.62 nm to 1952.63 nm are also obtained. The generated soliton pulses can be precisely tuned between 1971.62 nm and 1952.63 nm by controlling the temperature of the AFLF.