NTT Research and Development 2010 Review of Activities

Overview

To cope with the explosive increase in data traffic, there is a need for higher-speed networks. To lower network costs, the transmission reach of optical signals needs to be extended. NTT Photonics Laboratories are researching optical devices that can enable high-speed (>100 Gbit/s/ch) and long-reach (>1,000 km) networks. Such devices can be fabricated using planar lightwave circuits (PLCs), optical semiconductors, and high-speed electrical semiconductors, which have enabled NTT to set world records for high-speed, long-reach optical transmission.

Features

Optical transmitters and receivers are quite complex because the modulation format of a transmission uses an optical phase as well as an optical amplitude.

• These complex transmitters and receivers have been stably and compactly fabricated
• Optical Transmitters: Integration of PLCs and LiNbO₃ (LN) optical modulator (e.g. 64-QAM 240-Gbit/s optical signal generation)
• Optical Receivers: Integration of PLCs, photodiodes (PDs), and transimpedance amplifiers(TIAs) (e.g. DP-QPSK 100-Gbit/s optical signal receiver)

Application scenarios

• Near-future high-speed, long-reach communication networks (>100-Gbit/s/ch optical transmission systems)
• Very-high-speed optical access networks

• This work is partly supported by the R&D on High-speed Optical Transport System Technologies of the Ministry of Internal Affairs and Communications (MIC) of Japan.