There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Jasmonates: biosynthesis, perception, signal transduction and action in plant stress response, growth and development. An update to the 2007 review in Annals of Botany

This Review covers the state-of-the-art technologies on photonics-based terahertz communications, which are compared with competing technologies based on electronics and free-space optical communications. Future prospects and challenges are also discussed. Almost 15 years have passed since the initial demonstrations of terahertz (THz) wireless communications were made using both pulsed and continuous waves. THz technologies are attracting great interest and are expected to meet the ever-increasing demand for high-capacity wireless communications. Here, we review the latest trends in THz communications research, focusing on how photonics technologies have played a key role in the development of first-age THz communication systems. We also provide a comparison with other competitive technologies, such as THz transceivers enabled by electronic devices as well as free-space lightwave communications.

/pdf/advances-in-terahertz-communications-accelerated-by-t151adrqkd.pdf

Advances in terahertz communications accelerated by photonics

Wave propagation and group velocity

A wireless communication system with a maximum data rate of 100 Gbit s−1 over 20 m is demonstrated using a carrier frequency of 237.5 GHz. The photonic schemes used to generate the signal carrier and local oscillator are described, as is the fast photodetector used as a mixer for data extraction.

Wireless sub-THz communication system with high data rate

Performance Analysis of Fixed-length, Variable-capacity Optical Packet Switching Networks (光通信システム) -- (光アクセスシステム特集)

We analytically investigate the computational complexity of MIMO processing in mode-division multiplexing (MDM) transmission over 2-mode fiber (2MF) and discuss the feasibility of long-haul MDM transmission utilize graded-index 2MF.

On the Computational Complexity of MIMO Processing in Mode Division Multiplexing Transmission over 2-mode Fiber

We demonstrate C-band 112Gb/s PAM4 over 50km single-mode fiber enabled by joint OE-FFE. An optical single-tap delay line and record-low-complexity 31-tap symbol-spaced FFE suffice to achieve 6.7% HD-FEC-compliant BER. 60Gb/s ZR transmission is also reported.

C-band Single-lane 100G ER and 50G ZR PAM Transmissions based on Joint Optical-electrical Feedforward Equalization (OE-FFE) with Record-low Complexity

This paper describes a scenario of highly resilient mobile backhaul using the radio-over-fiber (RoF) technology. RoF-based millimeter-wave high-speed transmission is useful for quick recovery from severe physical damage of the network infrastructure. As a possible approach, we demonstrated polarization division multiplexing optical and 2×2 multi-input multi-output radio seamless hybrid downlink transmission over 20-km-long standard single mode fiber and 0.9-m free space with a digital signal processing technique for the 10-Gbaud QPSK format.

Digital-signal-processing-aided ultra-high-speed radio-over-fiber technology for highly resilient mobile backhaul

After the nuclear power plant disaster, the evaluation of radioactive Cs kept in soil, especially in clay minerals and the elucidation of its movement are urgent subjects to promote decontamination. It is known that the extractable level of Cs depends on the sort of clay minerals. We tried to find the characteristics of clay minerals belonging to phillosilicate group using positron annihilation spectroscopy (PAS) and the relationship between the results of PAS and the amounts of substantially extracted Cs from the clay minerals. The results showed that each clay mineral was found to be distinguishable from other clay minerals by PAS and the extraction rate of Cs was different among those clay minerals, however the direct correlation between the results of PAS and the extraction rates of Cs was not found.

https://iopscience.iop.org/article/10.1088/1742-6596/618/1/012037/pdf

Yuki Yoshida

Papers

Performance Analysis of Fixed-length, Variable-capacity Optical Packet Switching Networks (光通信システム) -- (光アクセスシステム特集)

On the Computational Complexity of MIMO Processing in Mode Division Multiplexing Transmission over 2-mode Fiber

C-band Single-lane 100G ER and 50G ZR PAM Transmissions based on Joint Optical-electrical Feedforward Equalization (OE-FFE) with Record-low Complexity

Digital-signal-processing-aided ultra-high-speed radio-over-fiber technology for highly resilient mobile backhaul

Feasibility of classification of clay minerals by using PAS