Abstract

Repeaterless long-span transmission is now actively studied for undersea inter-island, island-mainland, and coastal links or terrestrial remote terminal links. The main emphasis is on maximizing T-R power budget while minimizing fiber dispersion effects. Recent advances in erbium-doped fiber amplifiers (EDFAs) offer a significant increase in the T-R loss budget in the 1.5-μm wavelength region. Consequently, the fiber dispersion issue becomes even more important in EDFA-based long-distance transmission systems. Among various approaches to alleviate the fiber chromatic dispersion effect, intensity modulation/direct-detection (IM/DD) using an externa) modulator is the most promising because it offers an information bandwidth-limited optical signal and therefore a small dispersion penalty even with standard nondispersion shifted fibers (non-DSFs).² In addition, it is relatively straightforward to fabricate.

© 1992 Optical Society of America