Katsunori Imamura

19-core fiber transmission of 19×100×172-Gb/s SDM-WDM-PDM-QPSK signals at 305Tb/s

A novel free-space coupling system combined with a multi-core fiber enables up-scaling to a record space-division-multiplexed (SDM) channel number of 19. We achieve 305-Tb/s transmission over 10.1 km using 19-SDM, 100-WDM PDM-QPSK signals.

305 Tb/s Space Division Multiplexed Transmission Using Homogeneous 19-Core Fiber

We report record capacity data transmission at 305 Tb/s over 10.1 km, using space division multiplexing (SDM) with 19 channels. To realize such a large SDM channel number, we fabricated a trench-assisted homogeneous 19-core fiber with average intercore crosstalk of about -32 dB at 1550 nm. We also fabricated a 19-channel SDM multiplexer/demultiplexer using free-space optics with low insertion losses and low additional crosstalk. The data signal transmitted through each SDM channel was 100 wavelength division multiplexing (100 GHz spacing) 2 × 86 Gb/s polarization-division-multiplexed quadrature phase shift keying signals and the spectral efficiency was 30.5 b/s/Hz.

Investigation on multi-core fibers with large Aeff and low micro bending loss

For large Aeff Multi-Core Fibers (MCFs), advantages of using holey fibers as well as effective ways with solid fibers were confirmed. The solid MCFs with Aeff >100 μm2 and suppressed micro bending loss were actually fabricated.

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.

Development of fiber bundle type fan-out for multicore fiber

We developed a compact fiber bundle type fan-out for multicore fiber by using capillary action of adhesive. The fan-out demonstrated low splice loss less than 0.35dB and low cross-talk less than -64dB in all cores.

Effective space division multiplexing by Multi-Core Fibers

The minimum fiber diameter of Multi-Core SMF was investigated taking the cladding diameter, core pitch and attenuation loss into account. A way to suppress the failure rate in case of high core density was also discussed.

Multi-core holey fibers for ultra large capacity wide-band transmission

Multi-core holey fibers for the ultra large capacity transmission were investigated numerically and experimentally. Each core can realize the ultra wide band transmission over 550-1700 nm.

Comparisons of merits on wide-band transmission systems between Using extremely improved solid SMFs with Aeff of 160μm 2 and loss of 0.175dB/km and Using large-Aeff holey fibers enabling transmission over 600nm bandwidth

Low-loss and large-Aeff SMFs as well as DCFs for S, C, L-band compensation were numerically optimized and fabricated. Merits of using holey fibers in case of ultra wide-band transmission over 600 nm will be also demonstrated.