A difference frequency generation scheme that is potentially applicable to self-stabilization of the carrier-envelope-offset phase is demonstrated for the first time with a fiber-laser-based system. By taking advantage of the unique dispersion of the photonic-crystal-fibers, short pulses at 615 nm can be efficiently and selectively generated with low noise via Cherenkov-radiation in a 23-mm-PCF with a mode-locked Yb-fiber laser. Difference frequency generation between the 615-nm pulses and the 1030-nm output pulses from the Yb-fiber amplifier produces pulses at ~1530 nm, which can be readily amplified by Er-doped-fiber amplifiers. This scheme may provide a new route to a fiber-laser-based CEO-phasestabilized source.