May 2023 Vol. 21 No. 5

View from the Top

• Hiroshi Tomiyasu, Senior Vice President, Head of Technology and Innovation General Headquarters, NTT DATA

  

  Abstract
  NTT DATA creates new systems and value using information technology to contribute to creating a more prosperous and harmonious society. In accordance with the five strategies laid out in its medium-term management plan for FY 2022 to 2025, the company aims to establish a virtuous cycle of investment and growth and achieve business growth toward the Global 3rd Stage. Hiroshi Tomiyasu, senior vice president and head of Technology and Innovation General Headquarters, NTT DATA, is leading efforts toward this goal in terms of technology. We interviewed him about specific technology strategies and his belief as a top executive.

Front-line Researchers

• Masaya Notomi, Senior Distinguished Researcher, NTT Basic Research Laboratories and Project Leader of NTT Nanophotonics Center

  

  Abstract
  NTT Nanophotonics Center is investigating photonics-electronics convergence technologies with the aim of creating low-latency and low-energy-consumption optical computing technology. As various types of photonic information processing are becoming possible, Masaya Notomi, a senior distinguished researcher at NTT Basic Research Laboratories and project leader of NTT Nanophotonics Center, is pursuing the control of optical properties of materials and device applications by using artificial nanostructures. We interviewed him about the progress of his research activities and his attitude as a researcher.

Rising Researchers

• Yasufumi Ogawa, Distinguished Researcher, NTT Network Innovation Center

  

  Abstract
  As network services become increasingly diversified, the difficulty of predicting and dealing with spikes and fluctuations in data communications traffic is becoming apparent. However, studies are now underway at many telecom operators on ways of solving this problem by applying network virtualization technology for a network functions virtualization (NFV) infrastructure (software virtualization) to network services. In this article, we talked with Distinguished Researcher Yasufumi Ogawa about network virtualization technology for an NFV infrastructure.

Feature Articles: Plasmon Control Technology

• Overview and Prospects for Research on Plasmons in Two-dimensional Semiconductor Systems

  

  Abstract
  Plasmons, which are collective oscillations of electric charges, have a wide range of applications in sensors and other technologies. Plasmons have also been attracting attention as potential new information carriers due to their ability to be generated by light and propagate within a region that exceeds the diffraction limit of light. This article presents an overview of the research on plasmon control and basic physical properties exploiting plasmons at NTT Basic Research Laboratories. Future prospects are also discussed.

• Electrical Control of Plasmon Reflectivity in Graphene

  

  Abstract
  Properties of plasmons in graphene can be controlled electrically. My research colleagues and I have used this feature to verify that plasmons of desired frequencies can be excited in electrically specified regions. This technology can be applied to plasmonic devices such as waveguides and switches.

• Ultrafast Optical-to-electrical Conversion Processes in Graphene

  

  Abstract
  Graphene photodetectors have gained significant interest due to their predicted high sensitivity and rapid electrical response to broadband light, offering the potential for superior performance compared with conventional semiconductor devices. However, the experimental evaluation of the operation speed under a zero-bias voltage has been hindered by challenges associated with device architecture and measurement instrumentation, restricting the characterization of graphene’s intrinsic dynamics and clarification of its operating mechanism. This article presents an ultrafast graphene photodetector developed at NTT laboratories, detailing the measurement technology and operating mechanism.

• Theoretical Proposal for Edge Magnetoplasmon Crystal

  

  Abstract
  When a static magnetic field is applied to a two-dimensional electron system, plasmons appear at the edge of the specimen and exhibit peculiar behavior, such as the wave propagation to a single direction along the edge. The calculated results of investigating plasmon propagation when a sample is divided into regions and a crystalline network is formed indicate that the characteristics of the integer/fractional quantum Hall effect, which has been developed in various fields, can be reproduced as optical properties.

• Time-resolved Measurement of Ambipolar Plasmon Transport in Semiconductor Composite Quantum Wells

  

  Abstract
  Two-dimensional topological insulators have attracted much attention for potential application to quantum computers on the basis of a new principle. Semiconductor composite quantum wells, in which electrons and holes are confined in separate layers, can serve as two-dimensional topological insulators when their layer structure is optimized. We describe time-resolved measurements of ambipolar plasmon transport in both the electron and hole regimes separately using a single device. This technique will pave the way for investigations of charge and spin dynamics in two-dimensional topological insulators.

Regular Articles

• Ultrafast and Low-power-consumption Membrane Lasers on Si with Integrated Optical Feedback

  

  Abstract
  We developed energy-efficient membrane III-V distributed-reflector lasers on silicon-based substrates for ultrafast short-reach communication links and neuromorphic computing applications. By leveraging high-speed photon-photon interactions enabled by integrated optical feedback and a high-optical-confinement membrane structure, we demonstrated record-fast directly modulated laser bandwidths and spike-processing rates with ultralow operating energies. This is a step towards our goal of reducing the carbon footprint of information and communication technology and artificial intelligence hardware, while keeping pace with the increasing demand of processing speeds.

Global Standardization Activities

• Report of the First ITU-T TSAG Meeting for the 2022–2024 Study Period

  

  Abstract
  The first Telecommunication Standardization Advisory Group (TSAG) meeting for the 2022—2024 study period of the International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) was held from 12 to 16 December 2022 in a hybrid format at ITU Headquarters in Geneva and online. The main outcomes of this TSAG meeting, including the establishment of a Focus Group on Metaverse, are reported in this article.

Special Report

• 50th Anniversary of NTT Yokosuka R&D Center

  

  Abstract
  NTT Yokosuka R&D Center was established in November 1972 as the third research laboratory of the Nippon Telegraph and Telephone Public Corporation (the predecessor of NTT), and it celebrated its 50th anniversary in 2022. To commemorate this anniversary, the Center held a commemorative event on December 9, 2022. At the event, Mr. Shinjiro Koizumi, a member of the Japanese House of Representatives, and Mr. Katsuaki Kamiji, mayor of Yokosuka City, gave their greetings, and many executives from Yokosuka-based companies and organizations attended the event, which reaffirmed the bond between the Center and the community.

External Awards

• External Awards