Naomasa Shimojoh

1.05 Tbit/s WDM transmission over 8,186 km using distributed Raman amplifier repeaters

We have achieved a 1.05 Tera bit/s WDM transmission over 8186 km using distributed Raman amplifier repeaters. Signal bandwidth was 31.2 nm and the optical SNR improvement was about 1.5 dB in contrast to using an EDFA repeater.

128-Gbit/s WDM transmission of 24 5.3-Gbit/s RZ signals over 7828 km using gain equalization to compensate for asymmetry in EDFA gain characteristics

Erbium-doped fiber amplifiers (EDFAs) with broad signal bandwidth, low NF and high output power, and transmission characteristic improvement using chromatic dispersion management and modulation format are required for long-haul, wavelength-division multiplexing (WDM) transmission systems. We performed a 24 5.3-Gbit/s WDM transmission experiment over 7828 km using gain equalization to compensate for the asymmetry of the EDFA gain characteristics, RZ modulation format, and both pre- and post-compensation of chromatic dispersion.

Active Gain Slope Compensation in Large-Capacity, Long-Haul WDM Transmission System

Large-capacity, long-haul wavelength-division-multiplexing (WDM) transm1ss1on systems require broad WDM signal bandwidth, which can be expanded with broadband erbium-doped fiber amplifier (EDFA),1 gain-equalizer (GEQ),2,3 and pre-emphasis at the transmitter.

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.

20-nm signal bandwidth after 147-amplifier chain using long-period gain-equalizers

Summary form only given. Long-haul, large-capacity wavelength-division multiplexing (WDM) transmission systems require broad WDM signal bandwidth, which can be expanded with broadband erbium-doped fiber amplifiers (EDFAs), gain-equalizers (GEQs), and pre-emphasis of optical senders. Twenty-four WDM signals transmission over 2526 km with a 18.4-nm bandwidth and 16 WDM signals transmission over 6000 km with a 12-nm bandwidth have been reported. In this paper, we demonstrate a 20-nm WDM signal bandwidth after 147-amplifier chain (5958-km transmission) using high alumina co-doped EDFAs and long-period gain-equalizers (GEQs). The main GEQs have free-spectral-ranges (FSRs) of 48 nm, which are about two times as long as the wavelength difference between a 1558-nm EDFA gain peak and a 1536-nm EDFA gain valley.

Comparison between dispersion management for long-haul WDM systems using all-Raman-amplifier repeaters

We have numerically and experimentally compared the performance, in a WDM transmission system in which all repeaters are Raman amplifiers, of our proposed chromatic dispersion management and of a conventional dispersion management. The performance of our management was 1.6-dB better than that of the conventional management. Applying our management improved the OSNR by about 0.6 dB and reduced the amount of waveform distortion due to the nonlinear effect and group-velocity dispersion by 1.0 dB. We are convinced that our proposed dispersion management will be very effective for use with long-haul, high-capacity transmission systems in which all repeaters are Raman amplifiers and can be the best solution for the distributed Raman fibre amplification based system.

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.

1.22 Tbit/s WDM transmission over 7,221 km with 38 nm bandwidth expanded by distributed Raman amplifier and EDFA

By using a signal bandwidth expansion combined with a distributed Raman amplifier and an EDFA, we have achieved WDM transmission over 7,221 km at 1.22 Tbit/s in the L-band alone. The scheme seems to be more practical because it has relatively low loss gain equalization, the shorter wavelength OSNR improvement, and effective gain tilt compensation.

Flat gain profile in DRA-cascaded systems with fiber repair and pumping LD failure

Gain profile in cascaded distributed Raman amplification with increased span loss due to fiber repair and with pumping LD failure are investigated experimentally for the first time. We propose the counter-measures and present the effectiveness.

A Quarter Tb/s WDM Transmission Experiments over 2,526 km of Twenty-four, 10.664-Gb/s Data Channels using RZ Modulation Format

0. 256 Tb/s WDM signals were successfully transmitted over 2,526 km. WDM bandwidth of 18.4 nm was achieved using high alumina co-doped EDFAs and gain-equalizers. RZ modulation improved Q-factors by 2 dB.