An all polarization-maintaining fiber laser is established based on a nonlinear amplifying loop mirror, and thus a stable optical oscillator source is applied to an optical comb system which works outdoors. In this experiment, supercontinuum covering from 1000 nm to 2300 nm is produced by using two-level optical preamplification and high nonlinear fibers. The optimal signal-to-noise ratio of carrier-envelope offset frequency f₀ detected by the collinear f-2f interferometer is 35 dB. Furthermore, the relationship between the net cavity dispersion and the linewidth of f₀ is investigated. The narrowest linewidth of f₀ in the free-running mode is narrowed to 5 kHz. Finally, the repetition rate f_r and f₀ are both phase-locked to a rubidium atomic clock. The standard deviations for f_r and f₀ are 780 μHz and 308 mHz, respectively. The fiber optic comb system guarantees compact size and excellent integration level.