NTT Research and Development 2011 Review of Activities

Overview

Digital coherent optical transmission schemes with advanced modulation formats, such as M-QAM^*1 and OFDM^*2, are promising techniques for constructing future beyond-100-Gbit/s/ch optical communications systems. In the transmitter for such systems, ultrahigh-speed DACs^*3 are key components for generating complex modulated signals. NTT Laboratories have sophisticated ultrahigh-speed transistor, InP HBT^*4, technology and circuit design techniques, and have succeeded in developing ultrahigh-speed 6-bit DACs for such systems of the future.

Features

• The first 6-bit DAC that can operate at a sampling rate above 30 GS/s
• Provides various modulated signals, such as M-QAM and OFDM
• Uses our in-house ultrahigh-speed transistor, InP HBT, technology
• Novel circuit design techniques for ultrahigh-speed and low-power operation
• Uses broadband packaging technique

Application scenarios

• Future ultrahigh-speed and large-capacity optical communications systems
  (e.g. beyond-100-Gbit/s/ch optical communications systems)
• Future ultrahigh-speed optical access systems
• Measurement tools
  (e.g. ultrahigh-speed arbitrary waveform generator)

• *1 M-QAM: M-ary Quadrature Amplitude Modulation
• *2 OFDM: Orthogonal Frequency Division Multiplexing
• *3 DAC: Digital-to-Analog Converter
• *4 InP HBT: Indium Phosphide Heterojunction Bipolar Transistor