Femtosecond fiber oscillator with adjustable central wavelength and bandwidth optimized for high power amplification

We report an Yb-doped fiber laser oscillator that is generating femtosecond pulses with tunable spectral properties. Central wavelength and the bandwidth of the oscillator is adjusted via a manual iris aperture used as a spatial filter in the laser cavity. The tunability range of the central wavelength of the optical pulses generated from the oscillator is in the range of 1022 nm to 1038 nm and the bandwidth tunability range is 8 nm to 32 nm. The obtained pulses are all suitable for further amplification via fiber-based amplifiers and mostly in the mW average power range. The adjustability is satisfied by changing the aperture width and the system is open for improvement by adjusting the position of the filter too. We believe that this tunable oscillator is promising to be used as a seed for high power femtosecond pulse amplification schemes that necessitate certain central wavelength and bandwidth properties at the input of the amplifier and may enable more efficient and shorter pulse duration systems.