T. Terahara

Four 5-Gbit/s WDM transmission over 4760-km straight-line using pre- and post-dispersion compensation and FWM cross talk reduction

Summary form only given. In conclusion, four 5.332-Gbit/s optical WDM signals were successfully transmitted over 4760-km straight-line using pre and post-compensation of group velocity dispersion (GVD) for each channel and the reduction of four wave mixing (FWM) cross talk with high-speed polarization scrambling.

128/spl times/10.66 Gbit/s transmission over 840 km standard SMF with 140 km optical repeater spacing (30.4 dB loss) employing dual-band distributed Raman amplification

We present the first demonstration of a high-capacity (1.28 Tbit/s), long-haul (6/spl times/140 km) WDM transmission employing dual-band (C/L-band) distributed Raman amplification (DRA). The DRA improved OSNR and enabled an extra-long repeater spacing of 140 km.

Optical coherent broad-band transmission for long-haul and distribution systems using subcarrier multiplexing

The system configuration and future possibility of a coherent optical transmission system using subcarrier multiplex- ing (SCM) techniques are described. First, signal multiplexing techniques for coherent optical trans- mission are compared, and appropriate application for coherent SCM system is discussed. By comparing optical modulation meth- ods, optical frequency modulation (FM) using direct modulation of a DFB-LD and a heterodyne detection is shown to be feasible. lkansmission system using a configuration with a local laser in the transmitter is unaffected by polarization and is cost-effective. Phase noise can be suppressed by a phase-noise-canceling circuit (PNC) in a heterodyne receiver. This circuit is also effective for compensating for the frequency instability of light sources. A theoretical simulation of a coherent SCM system showed that a 100 channel of 30-MHz FM signal or a 15 channel of 155-Mb/s signal can be distributed to 10 000 subscribers using single stage or double stage optical amplifiers. To confirm the feasibility of coherent SCM transmission, pre- liminary experiments have been performed with optical FM by 2-channels 560-Mb/s ASK-SCM signal and a heterodyne detection using 3-electrode DFB-LDs. With a local LD setting at the transmitter, a span-loss margin of 40.7 dB was obtained using single stage Er3+-doped fiber amplifier (EDFA), and the system was insensitive to the state of polarization in the transmission fiber. In a subcarrier transmission of 560 Mb/s DPSK signal, the PNC effectively suppressed phase noise and the influence of IF frequency deviation. Finally, application of coherent SCM combined with optical frequency division multiplexing (OFDM) is discussed. A model allocation of optical carriers is proposed and possible receiving channel number is estimated.

Optimum span configuration of Raman-amplifier dispersion-managed fibers

We analyze the influence of the span structure on the performance of Raman-amplified dispersion-managed fibers. Our calculations show that a configuration with the dispersion compensating fiber placed in the span center achieves the best trade-off between optical signal-to-noise ratio and nonlinear effects.

3.5-Tbit/s (43-Gbit/s /spl times/ 88 ch) transmission over 600-km NZDSF with VIPA variable dispersion compensators

Summary form only given. We performed 3.5-Tbit/s (43-Gbit/s /spl times/ 88 ch) 600 km transmission in the C- and L-bands by using virtually imaged phased array (VIPA) variable dispersion compensators. An adequate OSNR, which was the same for all the channels, was obtained by using distributed Raman amplification (DRA), a gain equalizer (GEQ), and a pre-emphasis technique. VIPA variable dispersion compensators can thus effectively overcome the small dispersion tolerance and temporal dispersion changes of dense WDM terabit systems. We achieved a Q-factor of more than 11.8 dB (BER < 10/sup -17/ with FEC) for all 88 channels.

PDL-induced noise reduction in long-haul transmission systems using synchronous polarization scrambling

We proposed polarisation dependent loss (PDL) induced noise reduction method using a band-rejection-filter in a long-haul large-capacity WDM transmission system with synchronous polarization scrambling. We demonstrated the effect in an 8 channel 5.332 Gbit/s WDM transmission experiment using this method.

43-Gbit/s/spl times/40 ch transmission over 1,600 km of conventional single-mode fiber in NRZ modulation scheme

We demonstrate the feasibility of economical 40-Gbit/s WDM transmission over 1,600-km conventional single-mode fiber with simple NRZ modulation scheme employing two-stage dispersion compensating fiber Raman amplification and optimised dispersion map with excessive in-line dispersion compensation.

Long-haul WDM transmission system by use of high alumina codoped EDFAs and gain-equalizers

To expand the signal wavelength bandwidth in a long-haul, large-capacity WDM transmission system, we developed a high alumina codoped EDFA with broadband, high output power, and low noise figure using a 1480-nm pump laser. We applied gain-equalizers (GEQs) using Mach-Zehnder type optical filters with long free-spectral ranges to accurately compensate for the gain-wavelength characteristics of the EDFA. We investigated the signal wavelength bandwidth expanded by using the above EDFAs and GEQs. The achieved signal wavelength bandwidth after 10000-km transmission was 18 nm. We successfully transmitted 170 Gbit/s (32 channel/spl times/5.332 Gbit/s) WDM signals over 9879 km and 700 Gbit/s (66 channel/spl times/10.66 Gbit/s) WDM signals over 2212 km.