We presented a repetition-rate tunable Yb-doped fiber laser system, which used a chirped fiber Bragg grating as a fiber stretcher designed to match the 2nd and 3rd order dispersion of the transmission grating compressor. The system delivered 1-μJ, 143-fs pulse at 2 MHz repetition rate, and 10-μJ, 157-fs pulse at 200 kHz repetition rate, respectively. Pulse repetition-rate can be tuned from 200 kHz to 2 MHz while the pulse duration maintains <180 fs. This compact fiber laser source was built for applications in ophthalmology, such as corneal flap cutting and tissue vaporization. Furthermore, it can be applied in micro-machining, such as laser marking, scribing, and drilling.