An efficient gain-flattened L-band optical amplifier is demonstrated using a hybrid configuration with a distributed Raman amplifier (DRA) and an erbium-doped fiber amplifier (EDFA) for 160 × 10-Gb/s dense wavelength division multiplexed system at 25-GHz interval. With an input signal power of 3 mW, a flat gain of >; 10 dB is obtained across the frequency range from 187 to 190.975 THz with a gain variation of <; 4.5 dB without using any gain-flattening technique. The output power obtained at 3-mW optimum input power is also the highest value (>; 8.9 dBm) ever reported for a DRA-EDFA hybrid optical amplifier at reduced channel spacing.