We demonstrate here an environmentally stable and extremely compactable Er-doped fiber laser system capable of delivering sub-100-fs temporal duration and tens of nanojoules at a repetition rate of 10 MHz. This laser source employs a semiconductor saturable absorber mirror mode-locked soliton laser to generate seed pulses. A single-mode-fiber amplifier and a double-cladding-fiber amplifier (both with double-pass configuration) are bridged by a divider and used to manage the dispersion map and bo