Tomoyoshi Kataoka

Limitations and challenges of single-carrier full 40-Gbit/s repeater system based on optical equalization and new circuit design

A single-carrier 10-Gbit/s system was installed into commercial networks and wavelength-division multiplexing technology was employed in laboratory tests to accelerate the transmission capacity to speeds of up to 1 Tera-bit/s. This successful transmission capability is based on high-speed circuit technology. This paper describes the problems and solutions for a single-carrier system with speeds of 40 Gbit/s or more. There are two major problems in implementing this system: one is how fast can electrical and photonic circuits operate and the other is how to accommodate certain kinds of dispersion limitations in long-haul transmission.

Long-span repeaterless transmission systems with optical amplifiers using pulse width management

This paper proposes pulse width management in order to extend the repeater spacings of repeaterless transmission systems with optical amplifiers. First, the dependency of receiver sensitivity on duty ratio, receiver response, and fiber dispersion is clarified by numerical analysis. Next, the calculation results of sensitivity as a function of signal format and receiver basedband response are verified experimentally. Moreover, we show that pulse width management which uses return-to-zero (RZ) format with large duty ratio (/spl sim/0.7) at the transmitter and pulse compression at the receiver increases the repeater gain by /spl sim/4.5 dB compared to conventional systems employing nonreturn-to-zero (NRZ) format. Record repeater spacing of 300 km is realized at 10 Gb/s by utilizing pulse width management.

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.

Field transmission by using a commercially-ready 43 Gbit/s DWDM system employing RZ-DQPSK transponders in high PMD installed fiber

Using a commercially-ready 40-lambda DWDM system, RZ-DQPSK is confirmed to offer excellent DGD tolerance, up to 25 ps, through high PMD installed DSFs.

43-Gbit/s OTN interface prototype

Reports, for the first time, a 43-Gbit/s OTN interface prototype that implements more system functions than optical sending/reception, such as framing, scrambling/de-scrambling, client mapping, and supervisory functions, all with high performance.

Transmission line with distributed erbium-doped fiber amplifier

We show the advantages of distributed erbium-doped fiber amplifiers (EDFAs) over lumped EDFAs. Using the distributed EDFA for 50%-100% of the transmission line lessens the signal degradation compared to the conventional transmission line. We also show the feasibility of the gain-flattened d-EDFA transmission line. An experiment shows that the gain peak is shifted and flattened at low pump powers.

Automatic dispersion equalization by tunable laser for installation of high-speed optical transmission system

In high-speed transmission systems, group velocity dispersion (GVD) equalization is indispensable if previously installed fiber cables are used because they have various zero-dispersion wavelengths. From the viewpoint of economy, neither manual equalization nor worst-case system design is practical in future high-speed systems. This paper introduces automatic equalization for installation of future high-speed systems and a simplified system has been demonstrated; the GVD of a 10-Gbit/s 1000-km transmission line was successfully equalized in an automatic manner.

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.

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.