We propose and demonstrate a 10-Gb/s dense wavelength-division-multiplexing (DWDM) optical system based on a pulsed-seed-light source employing a fiber-based Mach-Zehnder interferometer (F-MZI) as an intensity noise suppressor. The transmission results show that the required injection power into a reflective modulator was as low as -18 dBm. The F-MZI can accommodate the polarized seed-light with superior noise characteristics so that the supported DWDM systems double using a single conventional unpolarized seed-light. In addition, an allowable length of the drop fiber is investigated to show the system flexibility.