2022 Fiscal Year Research-status Report
Photonic frequency converter for spectrally agile seamless access network in millimeter-wave band
| Project/Area Number |
22K04116
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| Research Institution | National Institute of Information and Communications Technology |
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Principal Investigator |
PHAM TIENDAT 国立研究開発法人情報通信研究機構, ネットワーク研究所フォトニックICT研究センター, 主任研究員 (50636321)
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| Co-Investigator(Kenkyū-buntansha) |
山口 祐也 国立研究開発法人情報通信研究機構, ネットワーク研究所フォトニックICT研究センター, 研究員 (30754791)
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| Project Period (FY) |
2022-04-01 – 2025-03-31
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| Keywords | radio over fiber / photonic down-conversion / fiber radio / optical communications |
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| Outline of Annual Research Achievements |
We studied photonic downconversion technology using single and dual wavelength modulation by a newly fabricated optical phase modulator. We compared the system characteristics and transmitted high-order quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) signals in the 43 and 52 GHz bands over the system. We also demonstrated the first radio-fiber-radio-fiber system for transparent delivery of 100-GHz radio signals in the uplink direction using photonic down-conversion. We successfully transmitted 16-QAM single-carrier and OFDM signals with line rates of 30 and 40 Gb/s over the system in the 100-GHz band. We proposed and developed a low-loss and high-bandwidth lithium niobate modulator integrated with an electro-optic frequency-domain equalizer. The fabricated Ti-diffused lithium niobate modulator has a low optical loss of 5.4 dB, low half-wave voltage of 3.7 V, and high bandwidth exceeding 110 GHz.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
We successfully developed the key devices for the project, including ultra-broadband optical phase and intensity modulators. We also studied and compared the key photonic down-conversion technologies and used them for signal transmission. For the system demonstration, we demonstrated the transmission, reception, and down-conversion of radio signals in different frequency bands, including at 43, 52, and 100 GHz bands using the developed devices and technologies. The achievements in the first year will be the basic for further studies in the next years. The achieved results have been presented at the top international conferences and published in high-impact journals.
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| Strategy for Future Research Activity |
We will work on higher frequency bands by developing a new optical modulator capable of operating in higher frequencies, such as beyond 110 GHz. The research on generation of a coherent two-tone optical signal with a frequency difference beyond 100 GHz will also be conducted and applied for photonic down-conversion of radio signals. We will use the developed devices and technologies for the system demonstration in the next years, including experiments on transmission of radio signals in beyond 110 GHz using photonic down-conversion technology in both downlink and uplink direction.
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| Causes of Carryover |
In fiscal year 2022, we could use our existed material and devices for the system demonstration and fabrication of the optical modulator. Therefore, some of the planned budget was not used and is transferred to the next fiscal year.
In the fiscal year 2023, we will buy some new material for fabrication of a new optical modulator capable of operating at higher frequency bands. We will also buy some devices, such as a frequency multiplier and RF connectors for developing a new two-tone optical signal generator at the high frequency band.
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