Tatsunori Omiya

256-QAM (64 Gb/s) Coherent Optical Transmission Over 160 km With an Optical Bandwidth of 5.4 GHz

We report a polarization-multiplexed (Pol-Mux) 4-Gsymbol/s 256 quadrature amplitude modulation (QAM) coherent optical transmission over 160 km. A 64-Gb/s data signal was successfully transmitted with an optical bandwidth of 5.4 GHz. We also describe a Pol-Mux, 10-Gsymbol/s, 128- and 64-QAM (140 and 120 Gb/s) transmission over 150 km.

512 QAM (54 Gbit/s) coherent optical transmission over 150 km with an optical bandwidth of 4.1 GHz

We report the first demonstration of 512 QAM coherent optical transmission by using an optical PLL. A polarisation-multiplexed 54 Gbit/s data signal was successfully transmitted at 3 Gsymbol/s with an optical bandwidth of 4.1 GHz including a tone signal.

400 Gbit/s 256 QAM-OFDM transmission over 720 km with a 14 bit/s/Hz spectral efficiency by using high-resolution FDE

We demonstrate 400 Gbit/s frequency-division-multiplexed and polarization-division-multiplexed 256 QAM-OFDM transmission over 720 km with a spectral efficiency of 14 bit/s/Hz by using high-resolution frequency domain equalization (FDE) and digital back-propagation (DBP) methods. A detailed analytical evaluation of the 256 QAM-OFDM transmission is also provided, which clarifies the influence of quantization error in the digital coherent receiver on the waveform distortion compensation with DBP.

Single-Channel 400-Gb/s OTDM-32 RZ/QAM Coherent Transmission Over 225 km Using an Optical Phase-Locked Loop Technique

A single-channel 400-Gb/s transmission with a polarization-multiplexed , 10-Gsymbol/s, four-optical time-division multiplexed (OTDM) 32 return-to-zero/quadrature amplitude modulation (RZ/QAM) scheme is demonstrated for the first time. By using an optical phase-locked loop technique and a clock recovery circuit, we have successfully obtained a very stable pulsed-local oscillator whose phase was locked to the transmitter, and achieved precise demultiplexing and demodulation simultaneously. As a result, 400-Gb/s data were transmitted over 225 km with a bit-error-rate performance below the forward-error correction limit. Furthermore, we also realized a 320-Gb/s to 450-km transmission with an OTDM 16 RZ/QAM scheme.

256 QAM (64 Gbit/s) coherent optical transmission over 160 km with an optical bandwidth of 5.4 GHz

We present the first demonstration of 256 QAM coherent optical transmission, where 64 Gbit/s polarization-multiplexed data at 4 Gsymbol/s were successfully transmitted over 160 km with an optical bandwidth of only 5.4 GHz.

Marked performance improvement of 256 QAM transmission using a digital back-propagation method

We demonstrate substantial performance improvements in 256 QAM transmission in terms of both data rate and distance that we realized by using a digital back-propagation (DBP) method. 160 Gbit/s-160 km and 64 Gbit/s-560 km transmissions were successfully achieved with a polarization-multiplexed 256 QAM signal, in which the symbol rate and transmission distance were greatly increased by compensating for the interplay between dispersion and nonlinearity, which is responsible for the transmission impairment especially for a higher symbol rate and longer distance.

512 QAM transmission over 240 km using frequency-domain equalization in a digital coherent receiver

We demonstrate a marked performance improvement in a 512 QAM transmission by employing frequency-domain equalization (FDE) instead of an FIR filter. FDE enables us to compensate for distortions due to hardware imperfections in the transmitter with higher precision, which successfully reduced the power penalty by 4 dB in a 54 Gbit/s (3 Gsymbol/s)-160 km transmission. FDE also allows the transmission distance to be extended up to 240 km.

120 Gbit/s, polarization-multiplexed 10 Gsymbol/s, 64 QAM coherent transmission over 150 km using an optical voltage controlled oscillator

We report a polarization-multiplexed, 10 Gsymbol/s 64 QAM coherent transmission over 150 km using an optical voltage controlled oscillator (OVCO). The OVCO enables us to realize a low phase noise optical phase-locked loop (OPLL) due to its wideband operation independent of the frequency modulation (FM) bandwidth of an LD. As a result, 120 Gbit/s, 64 QAM data were successfully transmitted over 150 km with a power penalty as low as 1 dB.

400 Gbit/s frequency-division-multiplexed and polarization-multiplexed 256 QAM-OFDM transmission over 400 km with a spectral efficiency of 14 bit/s/Hz

We demonstrate a 400-Gbit/s frequency-division-multiplexed and polarization-multiplexed OFDM transmission over 400 km (5×80 km SSMF) with 256 QAM subcarrier modulation using an optical PLL. A record spectral efficiency of 14 bit/s/Hz was successfully achieved.

Frequency division multiplexed 1 Gsymbol/s, 64 QAM coherent optical transmission with a spectral efficiency of 8.6 bit/s/Hz

We have successfully transmitted a three-channel frequency division multiplexed 1-Gsymbol/s, 64 QAM coherent optical signal over 160-km with a 1.4-GHz spacing. The spectral efficiency reaches as high as 8.6-bit/s/Hz.