Mitsunori Fukutoku

16-Channel X 10-Gbit/s Optical FDM Transmission Over a 1000 km Conventional Single-Mode Fiber Employing Dispersion-Compensating Fiber and Gain Equalization

Optical frequency-division-multiplexed (OFDM) networks are very attractive because the transmission capacity can be increased to over 100 Gbit/s [1] and network-oriented functions such as route-switching can be realized [2], However, fiber nonlinearity such as four-wave mixing (FWM) restricts the capacity-distance product [3], From the view point of FWM suppression and the practical use of existing fiber, conventional single-mode fiber (SMF) with dispersion compensation is a preferable option [4]-[7]. This paper reports the results of a 16-channel × 10-Gbit/s transmission experiment over 1000 km of SMF employing dispersion-compensating fiber (DCF).

Experimental demonstration of multi-degree colorless, directionless, contentionless ROADM for 127-Gbit/s PDM-QPSK transmission system

We experimentally demonstrate the feasibility of a multi-degree colorless, directionless, and contentionless (C/D/C-less) ROADM node composed of high port count wavelength-selective switches and transponder aggregators using silica-based planar lightwave circuit technology. The experimental results show that the introduction of a C/D/C-less function to a multi-degree ROADM node induces no significant penalty in a 127-Gbit/s PDM-QPSK signal transmission.

Multi-Layer Greenfield Re-Grooming with Wavelength Defragmentation

Flexible network design for multi-granular and quasi-dynamic traffic is important to minimize resource requirements. In the wavelength layer, wavelength blocking must also be reduced to achieve further cost reduction. We propose a novel traffic accommodation scheme based on repetitive Greenfield Re-grooming with Wavelength Defragmentation (GRWD), which is similar to storage-disk defragmentation. Numerical evaluation shows the required minimum number of sets of transport equipment for the proposed scheme.

Optimized multi-layer optical network using in-service ODU / wavelength path re-grooming

We propose a multi-layer network with in-service traffic re-grooming. The combination of colorless multi-degree ROADM and ODU cross-connect with ODU reallocation functionality can offer significant cost reduction with no impact of re-grooming on services.

Full-add/drop C/D/C-less ROADM achieved by developing arrayed optical amplifiers with a shared pump laser

We demonstrate the feasibility of arrayed optical amplifiers sharing a single pump laser to realize full-add/drop C/D/C-less ROADM nodes. Experimental results show that the arrayed optical amplifiers corresponded properly to the wavelength path reconfigurations by adjusting the splitting ratio of the splitter between the pump laser and eight EDFAs.

An EDFA gain control and power monitoring scheme for fault detection in WDM networks by employing a power-stabilized control channel

Schemes are proposed for the highly reliable gain control of erbium-doped fiber amplifiers (EDFAs) and for power monitoring to detect faults in wavelength-division-multiplexing (WDM) networks. These schemes employ one WDM channel (a control channel). The EDFA gain and output power levels are controlled by monitoring the control channel power that is automatically controlled and stabilized in the node. This prevents the uncontrolled EDFA operation that might result from any serious change in the control channel power. The use of a power stabilized control channel for power monitoring makes it possible to detect transmission system faults correctly because the monitoring of the control channel power is unaffected by the amplified spontaneous emission (ASE) generated in the EDFA. We also report experimental results on the dependence of the transient response of the EDFA gain and output power on the signal channel power and channel number input into the EDFA, when the power of the control channel changes due to problems with its light source. Numerical calculation of the gain transience explains the experimental results.

Multi-stage successive interference cancellation for spectrally-efficient super-Nyquist transmission

The use of multi-stage successive interference cancellation (M-SIC) for super-Nyquist transmission is proposed. Simulation and transmission experiment results showed carrier spacing was reduced by 20% for QPSK signals. Signal performance was enhanced when M-SIC was used with non-uniform power transmission.

Hybrid 40-Gb/s and 100-Gb/s PDM-QPSK DWDM transmission using real-time DSP in field testbed

We demonstrate hybrid 40-Gb/s and 100-Gb/s PDM-QPSK DWDM transmission using real-time DSP in 580-km DSF-installed field testbed. The nonlinear crosstalk penalty due to the hybrid transmission of less than 0.5 dB is confirmed.

Experimental demonstration of arrayed optical amplifiers with a shared pump laser for realizing colorless, directionless, contentionless ROADM

We propose arrayed optical amplifiers that share a single pump laser with the aim of realizing full-add/drop colorless, directionless, contentionless ROADM nodes and demonstrate its feasibility in experiments. The experimental results show that the fabricated arrayed optical amplifiers can be made to correspond properly to wavelength path reconfigurations by adjusting a splitting ratio of the variable splitter between the pump laser and eight EDFAs, and cause no significant penalty for 128-Gbit/s PDM-QPSK signal transmission.

16 WDM optical packet routing experiment over 640 km transmission distance at data rate of 2.5 Gbit/s

We demonstrate 1024 byte, 16 wavelength-division multiplexed (WDM) optical packet transmission experiments including a wavelength routing function over 640-km transmission distance at the data rate of 2.5 Gbit/s. The bit error rate (BER) after 640 km transmission is 10-11 with no BER floor.