Abstract

Recently, 10 Gbit/s transmission systems with large loss budget were intensively researched.¹⁻³ Many studies on NRZ systems have tried to enhance the output power of the transmitters by the stimulated Brillouin scattering (SBS) suppressing scheme. High receiver sensitivities have been demonstrated^2,3 by using low noise optical pre-amplifiers and narrow band Fa-bry-Perot filters, which require precise control of central wavelength. On the other hand, it is pointed out that RZ transmissions have some good features; large output power without SBS suppression schemes, high receiver sensitivity without narrow band filters, and simplicity of clock recovery circuits. Short pulses, however, induce the large waveform distortion due to the self-phase modulation (SPM). While 300-km repeaterless transmission employing RZ pulses of 60-ps-wide was reported,¹ it is not clear that short pulses less than 50 ps could be transmitted over 200 km. In this paper, a 10 Gbit/s RZ transmission system with large loss budget is described and the repeaterless transmission employing short pulses of 24-ps-wide over 258 km is also discussed.

© 1996 Optical Society of America