Masateru Tadakuma

19-core MCF transmission system using EDFA with shared core pumping coupled via free-space optics

We report the development of a space division multiplexed (SDM) transmission system consisting of a 19-core fiber and 19-core Erbium-doped fiber amplifier (EDFA). A new 19-core fiber with an improved core arrangement was employed to achieve a low aggregated inter-core crosstalk of -42 dB at 1550 nm over 30 km. The EDFA uses shared free-space optics for pump beam combining and isolation, thus is SDM transparent and has some potential for cost reduction. 19.6 dB to 23.3 dB gain and 6.0 dB to 7.0 dB noise figure were obtained for each SDM channel at 1550 nm. System feasibility for SDM transmission over 1200 km was demonstrated with 100 Gb/s PDM-QPSK signals.

Super-Nyquist-WDM transmission over 7,326-km seven-core fiber with capacity-distance product of 1.03 Exabit/s · km.

We show super-Nyquist-WDM transmission technique, where optical signals with duobinary-pulse shaping can be wavelength-multiplexed with frequency spacing of below baudrate. Duobinary-pulse shaping can reduce the signal bandwidth to be a half of baudrate while controlling inter-symbol interference can be compensated by the maximum likelihood sequence estimation in a receiver. First, we experimentally evaluate crosstalk characteristics as a function of channel spacing between the dual-channel DP-QPSK signals with duobinary-pulse shaping. As a result, the crosstalk penalty can be almost negligible as far as the ratio of baudrate to frequency spacing is maintained to be less than 1.20. Next, we demonstrate 140.7-Tbit/s, 7,326-km transmission of 7 × 201-channel 25-GHz-spaced super-Nyquist-WDM 100-Gbit/s optical signals using seven-core fiber and full C-band seven-core EDFAs. To the best of our knowledge, this is one of the first reports of high-capacity transmission experiments with capacity-distance product in excess of 1 Exabit/s · km.

110.9-Tbit/s SDM transmission over 6,370 km using a full C-band seven-core EDFA

We confirm the feasibility of 100-Tbit/s-class trans-oceanic SDM transmission. Using seven-core fiber spans with seven-core full C-band EDFAs, 7 × 264-channel quasi-Nyquist-WDM 60-Gbit/s PDM-QPSK signals are transmitted over 6,370 km.

Polarization insensitive arbitrary wavelength conversion in entire C-band using a PM-HNLF

Polarization insensitive pump-wavelength-tunable FWM in a zero dispersion and dispersion slope PM-HNLF was demonstrated. Polarization scrambled 10Gbit/s NRZ and DPSK signals in entire C-band were converted into entire C-band with power penalties less than 0.3dB and 0.5dB, respectively.

Cladding-Pumped L-Band Multicore EDFA with Reduced Power Consumption

Seven-core MC-EDFA pumped with single MM-LD optimized for L-band is developed. Output power of 19 dBm for each core is realized between 1576-1603nm with 33% reduced power consumption.

FWM wavelength conversion with over 60nm of 0dB conversion bandwidth by SBS-suppressed HNLF

We demonstrated FWM wavelength conversion with maximum conversion efficiency of 1.5 dB using a single CW pump with no phase modulation by SBS-suppressed HNLF. Over 60 nm of conversion bandwidth with over-0 dB conversion efficiency was obtained.

SBS suppression techniques in highly nonlinear fibers

We summarize the state of the art SBS suppression techniques in HNLFs. Novel design for SBS suppression of HNLFs are discussed, and the impact of an efficient SBS suppression is introduced.

Experiment of zero dispersion tuning by stretching down-sized HNLF

Zero dispersion of drawn HNLF was tuned by fiber stretching. Small cladding fiber is attractive for this purpose. 16nm tuning range of ¿0 was realized and performance of this tuning was confirmed by FWM wavelength conversion experiments.

Multicore EDFA to realize simultaneous excitation with cladding-pumped technology

We report some recent research activities of multicore EDFAs with cladding-pumped technology. We successfully developed cladding-pumped MC-EDFAs with C-band L-band application, respectively. Cladding-pumped L-band MC-EDFA realized output power of 19 dBm for each core between 1576-1603 nm with 33 % reduced power consumption.

Wideband parametric processing with 1-dB bandwidth of 40nm using dispersion stable PM-HNLF

We confirm the widest parametric processing bandwidth of a dispersion stable polarisation maintaining (PM) highly nonlinear fibre (HNLF) among PM-HNLFs. A wavelength conversion and a quasi-phase-matched FOPA with gain of 19 dB have 1-dB bandwidth of 40 nm.