Long-distance transmission of directly modulated 1550 nm AM-VSB CATV systems

This study presents a directly modulated 1550 nm NTSC AM-VSB 74-channel fib er optical CATV long-distance (over 100 km) transmission system. In this sy stem, 1550 nm analog distributed feedback (DFB) laser diodes, push-pull pre amplifier, half-split-band, wavelength-division-multiplexing (WDM), and in- line erbium-doped fiber amplifiers (EDFAs) were used. Performances of carri er-to-noise ratio (CNR) of greater than or equal to 49 dB, compositie secon d order (CSO) of greater than or equal to 70 dB, and composite triple beat (CTB) of greater than or equal to 65 dB were obtained over 100 km of standa rd single-mode fiber (SMF) transmission. This proposed directly modulated t ransmission system is simpler and more cost-effective than conventionally e xternally modulated 1550 nm transmission systems.