We demonstrate a simple and compact Holmium-doped fiber (HDF) femtosecond oscillator with 35 MHz repetition rate.
The oscillator is pumped by a Tm-doped fiber laser. A dispersion compensating fiber was utilized to set the net-intracavity
dispersion to zero at 2.06 μm. The output pulses had an maximum average power of 40 mW and 160 fs FWHM
pulse duration. To further shorten the pulse duration, we implemented a nonlinear compressor consisting of a solid core
highly nonlinear fiber (HNLF) for SPM broadening and single mode fiber (SMF) for pulse compression. Sub-100 fs
pulses were achieved.