Kenichi Kashima

Bias-Free Operational UTC-PD above 110 GHz and Its Application to High Baud Rate Fixed-Fiber Communication and W-Band Photonic Wireless Communication

We present the design of a bias-free uni-travelling-carrier photodiode (UTC-PD) that is operational above 110 GHz, and its application to 100-GBd fixed-fiber communication and 109-GHz carrier-photonic wireless communication for advanced optical networks. The design and analysis for bias-free operation were explained in detail using the carrier concentration in the photo-absorption layer and carrier collector layer. In the experimental results, the developed UTC-PD with back-illuminated structure exhibited a wide 3-dB bandwidth of over 110 GHz at 0 V. For fixed-fiber communications, a high-baud-rate photoreceiver based on the UTC-PD was fabricated. Eye diagrams showed clear openings at up to 107 GBd and high photo-currents of 3-7 mA at 100 GHz signal light were observed at zero-bias. Assuming photonic wireless communication using photonic power supply through optical fiber, the developed UTC-PD contributed to reducing bias feeds to the photoreceiver module. Additionally, low power consumption was achieved when using the newly developed 110 GHz InP-PHEMT amplifier with the UTC-PD.

100-GHz Fiber-Fed Optical-To-Radio Converter for Radio-And Power-Over-Fiber Transmission

We have developed a 100-GHz fiber-fed optical-to-radio converter for radio- and power-over-fiber transmission. A zero-bias operational high-speed photodetector (3-dB bandwidth >100 GHz) could be applied for the optical-to-radio converter, taking significant advantage of no-bias feed 100-GHz operation. We have successfully demonstrated simultaneous radio and power generation from one device through a bias-T circuit. A 100-GHz pseudomorphic high electron mobility transistor amplifier allowed a hybrid integrated photoreceiver to enhance the O/E conversion gain. Using the generated electric power, a gate bias in the 100-GHz amplifier was driven. The performance of each device and the integrated photoreceiver is described. High data rate photonic wireless transmission based on photonic power supply without external electric power supply is demonstrated.

Radio over fiber signal generation and distribution and its application to train communication network

Radio over fiber signal generation by an ultra-fast wavelength-tunable laser under wavelength-division-multiplexing configuration is demonstrated for radio signal delivery to remote sites in a linear-cell-based distributed antenna system. Application to linear-cell train communication system is discussed.

High conversion gain, low power consumption W-band photoreceiver integrated with UTC-PD and InP-PHEMT amplifier

In this study, we successfully fabricated a W-band high-power photoreceiver with high output power and low power consumption. This W-band photoreceiver was integrated with a bias-free uni-travelling carrier photodetector (UTC-PD) and an InP high electron mobility transistor (PHEMT) amplifier for the first time. An ultrabroad 3 dB bandwidth beyond 110 GHz in an UTC-PD and maximum oscillation frequency of 320 GHz in a PHEMT low-noise amplifier were used for this hybrid integration. At 109 GHz, a high radio frequency output power of +10 dBm, high transimpedance gain of 828 □, and low power consumption of 67 mW was achieved in an optical-electrical converting process.

Real-Time 10GbE Data Transmission Over a Converged RoF Links and 96-GHz Wireless Bridge

In this letter, we present a proof-of-concept of a realtime 10-Gigabit Ethernet (10GbE) standard data connectivity over a seamlessly converged intermediate frequency IF-overfiber and millimeter wave links with remotely fed optical local oscillator (LO) signals. We demonstrate an error-free real-time transmission of π/4-DQPSK-mapped 10GbE frames at 5-Gbit/s over 2×20-km single mode fiber and 20-m W-band (i.e., 96 GHz) wireless bridge. The 10GbE traffic is adjusted to the actual system capacity and transmitted using two parallel channels with a maximum rate of 1.25-GBaud per channel. We experimentally investigate and evaluate the impact of RoF and W-band links characteristics on the overall system performance. The obtained results demonstrate the potential use of the proposed system for the next generation agile and resilient access networks.

100 GHz optical-to-radio converter module and its application in radio and power over fiber transmission through multi-core fiber

We developed a 100 GHz optical-to-radio converter module integrated with a 100 GHz amplifier, which was applied in radio (12-Gbps, OFDM, 16-QAM, IF = 92-GHz) and power over fiber transmission through a multi-core fiber.

Performance evaluation of real-time 10GbE data connectivity over a converged IF-over-Fiber links and millimeter-wave wireless bridge

In in this paper, we present a proof-of-concept of a real-time 10GbE standard data connectivity and ultra-highdefinition (UHD) video streaming over a seamlessly converged intermediate frequency (IF)-over fiber (IFoF) and millimeter-Wave (mmWave) links. We successfully transmit π/4-DQPSK mapped Ethernet frames at 4.6 Gbps capacity over 2×20-km single mode fiber (SMF) links and 20-m W-band (i.e. 96-GHz) wireless bridge. We also demonstrate an error-free live steaming of 36 compressed 8K UHD videos with a total data-rate of 4.3 Gbps. Moreover, the impact of IFoF and W-band links characteristics on the system performance is experimentally investigated and evaluated. Based on the proposed system performance, we further estimate the achievable W-band transmission distance for both fair and heavy rain weather conditions. The obtained results confirm the potential use of mmWave-IFoF links for reliable high bandwidth GbE data connectivity, in particular for applications such as quick disaster recovery, temporary dense communication area, and large-scale live relay broadcasting of UHD-TV programs.