October 2019 Vol. 17 No. 10102019

https://www.ntt-review.jp/archive/2019/201910.html

Feature Articles
Creating Novel Functional Materials
Overview of Novel Materials Creation Research at NTT
Creation of Novel Material Sr3OsO6 with the Highest
Ferromagnetic Transition Temperature among Insulators
Magnetically Purified Erbium-doped Oxide Crystal—
Towards Creating a Quantum-information-manipulation
Platform
MBE Growth and Element-distinctive Atomic-resolution
Characterization of High Temperature Superconductors
High-quality Atomic-layer Materials Fabricated byChemical Vapor Deposition
Development of Next-generation Wide-bandgap
Semiconductors
Crystal Growth of Wurtzite GaP Nanowires for
Solar-water-splitting Devices

Regular Articles
High Power and High Efficiency Operation of Semiconductor Optical Amplifier Assisted Extended
Reach Electroabsorption Modulated DFB Laser (AXEL) for Extension of Transmission DistanceFeature Articles
Creating Novel Functional Materials

Overview of Novel Materials Creation Research at NTT▼Abstract
The activities of NTT Basic Research Laboratories include creating novel materials with fascinating
functions through materials design and arrangement control of atoms, molecules, and crystals in materials.
The purpose is to make progress in materials science and eventually contribute to the development of
information and communication technology. While our research covers a vast range of materials, we
introduce some of the latest research accomplishments in inorganic materials, for example, oxides andnitrides, in the Feature Articles in this issue. In particular, we highlight thin films (less than a micrometerthick), atomic layer materials (less than a nanometer thick), and nanowires.

Regular Articles

High Power and High Efficiency Operation of Semiconductor
Optical Amplifier Assisted Extended Reach
Electroabsorption Modulated DFB Laser (AXEL) forExtension of Transmission Distance▼Abstract

Global Standardization Activities
Surviving in the Digital Transformation Era; Technical Trends and Issues from the Perspective ofThe Telecommunication Technology Committee

Practical Field Information about Telecommunication
Technologies
Introduction to Troubleshooting Cases Related to Telephone Systems in Customer Premises

We have designed a semiconductor optical amplifier integrated with an electroabsorption modulator
integrated distributed feedback laser (EML). We call this device AXEL; it is designed to enhance the power
conversion efficiency and modulated light output power of EMLs. In this study, we investigated AXELs forboth the L-band and O-band wavelength ranges. The results of experiments indicated that dramaticallyincreased power conversion efficiency and modulated light output power were obtained with the fabricated
AXELs. For the L-band wavelength range AXEL, a high modulated light output power of 9 dBm and anextension of 10-Gbit/s transmission distance to 80 km due to low chirp characteristics of the AXEL weresimultaneously demonstrated. In addition, the 25-Gbit/s 80-km transmission achieved using the O-band
wavelength range AXEL along with an avalanche photodiode was demonstrated for the first time thanks tothe significantly increased modulated light output power of the AXEL.