Wavelength- and dispersion-tunable ultrafast holmium-doped fiber laser with dual-color operation

We present a versatile ultrafast holmium-doped fiber laser with an intracavity Martinez compressor. The compressor enables continuous dispersion control, spectral filtering, and dual-color operation of the laser. Mode locking is supported for net cavity dispersion values ranging from highly anomalous (-1.42ps²) to net normal (0.3ps²), and wavelength tuning of the optical solitons is obtained in a 2021-2096 nm span. Dual-color pulsed operation of the laser is reached by implementing a mechanical bandstop filter within the compressor. The repetition rate offset of the two emitted frequency combs can be tuned in a 3-8 kHz range by adjusting the net cavity dispersion, or by changing the beam block diameter. We show that a relatively simple fiber resonator integrated with a Martinez compressor can serve as a highly tunable laser source.