Kompetenzzentrum für optische Spezialfasern

We demonstrate a widely tunable Q-switched dual-wavelength fiber laser emitting synchronized pulses in the 2 µm spectral range. Owing to the use of a thulium doped rod-type Fully-Aperiodic Large Pitch Fiber (FA-LPF), together with an acousto-optic modulator (AOM), and two Volume Bragg Gratings (VBGs), the wavelength separation was shown to be continuously tunable from 1 nm to 120 nm (~0.1-10 THz). A peak power higher than 8 kW was demonstrated over the whole tuning range for a repetition rate of 1 KHz and a 26 ns pulse duration. The repetition rate was modulated from 1 kHz to 30 kHz, and the laser pulse duration measured between 23 ns and 130 ns, depending on the repetition rate and the wavelength separation.