Overview of Research in Laboratories

Materials Science Laboratory

Hiroki Hibino

The aim of this laboratory is to contribute to progress in materials science and to revolutionize information communication technology by creating novel materials and functions through material design at the atomic and molecular levels.

This laboratory consists of three research groups investigating a wide range of materials: e.g., typical compound semiconductors including GaAs and GaN, two-dimensional materials such as graphene, high-Tc oxide superconductors, and biomolecules. We are conducting innovative materials research based on advanced thin-film growth technologies along with high-precision and high-resolution measurements of structures and properties.

This year, we succeeded in the CVD growth of single-layer graphene composed of mm-sized single-crystalline domains. The self-heating effect has been suppressed in GaN-based electronic devices by transferring them to thermally conductive materials using our original epitaxial lift-off technique based on the cleavable nature of h-BN. In addition, the sensing fabric “hitoe”, which was developed last year in collaboration with Toray Industries, Inc., has been marketed by GOLDWIN Co. Ltd.

Physical Science Laboratory

Akira Fujiwara

The aim of the Physical Science Laboratory is to develop semiconductor- and superconductor-based devices and/or hybrid-type devices, which will have a revolutionary impact on the future ICT society. Research groups in our laboratory are using both high-quality crystal growth and nanolithography techniques that we have developed to explore novel properties that can lead to nanodevices for ultimate electronics and novel information processing devices based on new degrees of freedom such as single electrons, mechanical oscillations, quantum coherent states, electron correlation, and spins.

This year we realized the dynamic control of one-dimensional phononic crystals, observed Wigner solids in high magnetic fields, achieved high-speed single-electron transfer via a single-trap level in silicon, and observed dark states in a superconductor diamond quantum hybrid system. Progress was also made in the research on two-mode squeezing in an electromechanical resonator, the electric tuning of direct/indirect optical transitions in silicon, and resonant edge magnetoplasmons in graphene.

Optical Science Laboratory

Hideki Gotoh

The aims of this laboratory are to develop innovative core technologies for optical communications and optical signal processing, and to make fundamental scientific progress.

The groups in our laboratory are working to achieve quantum state control and quantum information processing by using very weak light, to discover intriguing phenomena by using very intense short pulse light, to control optical properties by using photonic crystals and ultrasonic techniques, and to characterize the unique properties of semiconductor nanostructures such as quantum dots and nanowires.

This year, we have succeeded in monitoring inner-shell electron motion with an ultrafast strobe light source using attosecond optical pulse creation techniques. We have also made progress on quantum key distribution employing superconducting detectors with an ultra-low-dark count rate and undertaken theoretical studies on quantum cryptography assuming realistic environments. In addition, we have clarified the quantum optical properties of silicon integrated optical circuits, revealed energy transfer processes in Er oxides, and fabricated a new type of semiconductor hetero-nanowire exploiting original self-catalyst growth techniques.

Nanophotonics Center

Masaya Notomi

The Nanophotonics Center was established in April 2012, and is now composed of several nanophotonics-related research groups from NTT Basic Research Laboratories and NTT Device Technology Laboratories. Our aim is to develop a full-fledged large-scale photonic integration technology that will allow us to densely integrate a large number of nano-scale photonic devices with various functions in a single chip. Furthermore, we are targeting an extreme reduction in energy consumption for photonic information processing by taking advantage of nanophotonics technology.

This year, we demonstrated an optical random access memory of over 100 bits based on ultrasmall integrated photonic crystal nanocavities. As a novel step, we realized InP nanowire and plasmonic nanoantenna coupled systems that showed substantial light emission enhancement. We also achieved large Raman enhancement in Si photonic crystal nanocavities with carbon nanotubes. As regards device applications, we achieved the room-temperature operation of on-Si photonic crystal nanolasers by employing a wafer-bonding technique, and demonstrated a spatial mode multiplexer/demultiplexer based on 3D multi-layer waveguides.