Yoshihisa Inada

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.

EDFA-Only WDM 4200-km Transmission of OFDM-16QAM and 32QAM

We experimentally demonstrated long-distance transmission of 68.3 Gb/s wavelength-division multiplexing polarization division multiplexing (PDM)-orthogonal frequency division multiplexing (OFDM)-16QAM and 85.5 Gb/s PDM-OFDM-32QAM signals. The PDM-OFDM-16QAM signals have been successfully transmitted over 4242 km with a net spectral efficiency of 5.46 b/s/Hz. Furthermore, utilizing multiband digital back-propagation for nonlinearity compensation, the PDM-OFDM-32QAM signals at 6.84 b/s/Hz net SE have been successfully transmitted over the same distance. After transmission, both 16QAM and 32QAM signals surpassed the 20% soft-decision forward error correction threshold. To the best of our knowledge, these results correspond to the longest transmission distance for the PDM-OFDM-16QAM and PDM-OFDM-32QAM signals with SE higher than 5 and 6.5 b/s/Hz, respectively, by employing only erbium doped fiber amplifier amplification.

6,050km transmission of 32 /spl times/ 42.7 Gb/s DWDM signals using Raman-amplified quadruple-hybrid span configuration

We demonstrate the first transatlantic distance transmission of 40-Gb/s-based dense-WDM signals with 100-GHz channel spacing. This successful transmission was achieved by suppression of fiber nonlinear effect enabled by distributed all-Raman amplification and a quadruple-hybrid span configuration.

3.2 Tb/s-1500 km WDM transmission experiment using 64 nm hybrid repeater amplifiers

3.2 Tb/s (160/spl times/20 Gb/s) RZ signals were transmitted over 1500 km precisely-flattened dispersion managed line with the use of newly developed 64 nm hybrid amplifiers. This is the first demonstration of multi terabit/s, long distance transmission.

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.

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.

Experimental study of non-binary LDPC coding for long-haul coherent optical QPSK transmissions

The performance of rate-0.8 4-ary LDPC code has been studied in a 50 GHz-spaced 40 Gb/s DWDM system with PDM-QPSK modulation. The net effective coding gain of 10 dB is obtained at BER of 10(-6). With the aid of time-interleaving polarization multiplexing and MAP detection, 10,560 km transmission over legacy dispersion managed fiber is achieved without any countable errors. The proposed nonbinary quasi-cyclic LDPC code achieves an uncoded BER threshold at 4×10(-2). Potential issues like phase ambiguity and coding length are also discussed when implementing LDPC in current coherent optical systems.

Optimized BICM-8QAM formats based on generalized mutual information

Through the expansion of non-Gray-mapping symbols, the pre-FEC and post-FEC Q-factors of the proposed optimized Circle-8QAM outperform Circle-8QAM and Star-8QAM by ~0.3 dB and ~0.6dB at the coding rate of 0.8 in experiments.