Takaaki Ogata

A new design arrangement of transmission fiber dispersion for suppressing nonlinear degradation in long-distance optical transmission systems with optical repeater amplifiers

The invention of the erbium-doped fiber amplifier has opened the possibility of constructing long-distance optical transmission systems with 1.5-mm zero-dispersion wavelength shifted fibers. In such systems, nonlinear degradation due to four-wave mixing and self-phase modulation strictly limits the total span of systems and the length of the optical repeater spacing. There are proposals to use slightly normal group velocity dispersion fibers (D >

40×117.6 Gb/s PDM-16QAM OFDM transmission over 10,181 km with soft-decision LDPC coding and nonlinearity compensation

Transmission of 117.6Gb/s optical PDM-16QAM OFDM signals over 10,181km is demonstrated at 25-GHz channel spacing with 4.7 b/s/Hz spectral efficiency. All the errors have been corrected by using 25% overhead QC-LDPC after multi-band nonlinearity compensation.

Observation of bit-error-rate impairment due to dynamic cross-phase modulation in 2.5 Gbit/s WDM transmission systems with standard fiber

Summary form only given. In this paper we have investigated high-power 2.5 Gbit/s WDM signal transmission property in a long-length conventional fiber. Severe bit-error-rate (DER) degradation due to dynamic cross phase modulation (CPM) between channels has been observed, that is dependent on the signal power and channel spacing. Further, we have demonstrated, by adequately setting the channel spacing, that the constraint can be relaxed and this resulted in successful transmission of four-channel 2.5 Gbit/s WDM signal over 360 km.

Compensation for chromatic dispersion and nonlinear effect in high dispersive coherent optical repeater transmission system

A design for a chromatic dispersion equalizer that provides 4.4 times higher efficiency in the dispersion compensation characteristics, compared with a conventional equalizer, is proposed. In addition, the amplitude response slope in the frequency domain is less than half of the conventional characteristic. This extends the compensation limit for chromatic dispersion up to 82500 ps/nm for a 2.5-Gb/s heterodyne system, which corresponds to a 4900-km normal dispersion fiber transmission system. A compensation method for modulational instability is also proposed. The method was confirmed by a 2.5-Gb/s continuous-phase frequency-shift-keying (CPFSK) 764-km normal dispersion fiber transmission experiment, with the abovementioned chromatic dispersion equalizer. Employing computer simulations, an over-1000-km normal dispersion fiber optical repeater transmission system with 2.5-Gb/s CPFSK heterodyne detection was shown to be feasible. >

Real-time 400G superchannel transmission using 100-GbE based 37.5-GHz spaced subcarriers with optical Nyquist shaping over 3,600-km DMF link

400G superchannel with four parallel 100-GbE subcarriers is successfully transmitted in real-time over 3600-km of DMF link using 150-GHz bandwidth. Optical Nyquist shaping is employed to reduce performance penalty induced by sharp optical filtering.

Next-generation 100 Gb/s undersea optical communications

100 Gb/s per channel optical communication is the natural next step for undersea DWDM optical communications. In this article we review some of the key advanced technologies that can have high impact on the future 100Gb/s undersea optical communications, and further present 100 Gb/s optical DWDM transmission over 10,000 km optical fibers.

4 × 1.15-Tb/s DP-QPSK superchannel transmission over 10,181-km of EDFA amplified hybrid large-core/ ultra low-loss fiber spans with 2-dB FEC margin

We report the first terabit/s superchannel transmission over a submarine distance >10,000 km. Four 1.15-Tb/s superchannels, each consisting of 23 optical subcarriers at 12.5-GHz spacing are modulated with DP-QPSK at 12.5 Gbaud. The WDM signal is transmitted over 168×60.6-km spans of hybrid large-core/ultra low-loss fibers with inline amplification by low noise C-band EDFAs. The system achieved a Q-factor margin of 2 dB assuming the use of HD-FEC, and a spectral efficiency of 3.6 b/s/Hz is achieved.

10 Gb/s, 16 channel unrepeated WDM transmission over 340 km of standard single mode fiber with very high power amplifier

160 Gb/s capacity (10.66 Gb/s, 16ch) unrepeatered transmission over 340 km of standard single-mode fiber has been demonstrated with a simple configuration in which only a remotely-pumped pre-amplifier and dispersion compensation fiber are employed with +30 dBm high power booster amplifier.

Estimation on maximum transmission distance for 2.5 Gb/s coherent FDM optical repeater systems

The transmission limit for the coherent FDM optical repeater transmission system is explained. On the basis of 2.5-Gb/s four-channel FDM optical-repeater transmission experiments, it was determined that four-wave mixing in the fiber is mainly what limits the maximum transmission distance to 1900 km with 50-km repeater spacing. In the region below this transmission limit, coherent detection was characterized by low power consumption characteristics in the optical repeaters.<<ETX>>

Trans-pacific transmission of quad-carrier 1Tb/s DP-8QAM assisted by LUT-based MAP algorithm

1Tb/s quad-carrier DP-8QAM transmission over 9280 km is reported at a spectral efficiency of 4.54 b/s/Hz thanks to the proposed joint transmitter maximum a posterior (MAP) pre-distortion and receiver correction scheme.