Kengo Horikoshi

69.1-Tb/s (432 × 171-Gb/s) C- and extended L-band transmission over 240 km Using PDM-16-QAM modulation and digital coherent detection

We demonstrate the record total capacity of 69.1 Tb/s with a spectral efficiency of 6.4 b/s/Hz by employing 21.4-Gbaud 16-QAM modulation, blind digital coherent detection, and 10.8-THz ultra-wideband amplification in the C- and extended L-bands.

Ultra-High Capacity WDM Transmission Using Spectrally-Efficient PDM 16-QAM Modulation and C- and Extended L-Band Wideband Optical Amplification

This paper describes ultrahigh capacity transmission based on spectrally-efficient multi-level modulation and wideband optical amplification techniques. 21.4-Gbaud polarization-division multiplexed (PDM) 16-ary quadrature amplitude modulation (QAM) signals are generated by utilizing an optical synthesis technique, wavelength-multiplexed with 25-GHz spacing by optical pre-filtering, and received by an intradyne coherent receiver based on digital signal processing (DSP) with pilotless algorithms. These techniques realize a spectral efficiency (SE) of 6.4 b/s/Hz. Furthermore, a hybrid amplification technique that combines distributed Raman and dual-band erbium-doped amplifiers (EDFAs) realizes 10.8-THz signal bandwidth in C- and extended L-bands. By using these techniques, we successfully demonstrate 69.1 Tb/s transmission over 240 km of low loss pure silica core fibers.

Coded Eight-Dimensional QAM Technique Using Iterative Soft-Output Decoding and Its Demonstration in High Baud-Rate Transmission

We proposed coded eight-dimensional (8-D) quadrature amplitude modulation (QAM) and experimentally demonstrated in high baud-rate transmission. Both high baud rate and multilevel modulation techniques are necessary for large capacity long haul transmission without increasing the number of transponders. However, optical signal-to-noise ratio (OSNR) tolerance of higher order modulation is low due to the short minimum Euclidean distance. Therefore, to relax OSNR tolerance by enlarging minimum Euclidean distance, we proposed 8-D modulation formats. The spectral efficiency of the proposed coded 8-D-16QAM, 8-D-32QAM, and 8-D-64QAM is equivalent to polarization division multiplexed (PDM)-8QAM, PDM-16QAM, and PDM-32QAM, respectively. To confirm the applicability of the proposed 8-D modulation to high baud rate transmission, we experimentally demonstrated 96-GBaud 8-D-16QAM wavelength division multiplexed transmission over 5,-252 km using iterative soft output decoding. The line data rate is 576-Gbps and a net rate 478-Gbps. At the same spectral efficiency, 8-D-16QAM using iterative soft output decoding can expand the transmission reach by 1212 km compared to conventional PDM-8QAM.