IEICE Electronics Express, Vol.8, No.8, 612–617 20-Gb/s QPSK W-band (75– 110 GHz) wireless link in free space using radio-over-ﬁber technique Atsushi Kanno 1a) , Keizo Inagaki 1 , Isao Morohashi 1 , Takahide Sakamoto 1 , Toshiaki Kuri 1 , Iwao Hosako 1 , Tetsuya Kawanishi 1 , Yuki Yoshida 2 , and Ken-ichi Kitayama 2 1 New Generation Network Research Center, National Institute of Information and Communications Technology 4–2–1 Nukui-kitamachi, Koganei, Tokyo 184–8795, Japan 2 Graduate School of Engineering, Osaka University Suita, Osaka 274–8601,Japan a) kanno@nict.go.jp Abstract: We demonstrate 20-Gb/s W-band wireless transmission in free space with a distance of 30 mm using optical signal genera- tion. Optically synthesized QPSK signal and direct optical upconver- sion technique ease generation of W-band RoF signals for dual purpose of wireline and wireless transmission link. A W-band radio receiver with W-band frequency downconversion and digital signal processing will be applicable for any W-band radio detection. Keywords: radio-over-ﬁber technique, quadrature-phase-shift-keying, wireless transmission Classiﬁcation: Fiber optics, Microwave photonics, Optical intercon- nection, Photonic signal processing, Photonic integration and systems References [1] Y. K. Huang, E. Ip, M.-F. Huang, Z. Wang, Y. Shao, Y. Aono, and T. Tajima, “1.5 Tb/s Super-channel Transmission over 1200 km SSMF us- ing All-Optical OFDM and Digital Coherent Receiver,” Asia Commun. Photon. Conf. (ACP 2010), Shanghai, China, PD 1, Dec. 2010. [2] H.-J. Song, K. Ajito, A. Wakatsuki, Y. Muramoto, N. Kukutsu, Y. Kado, and T. Nagatsuma, “Terahertz Wireless Communication Link at 300 GHz,” IEEE Intl. Topic. Meeting Microw. Photon. (MWP2010), Mon- treal, Canada, WE3-2, Oct. 2010. [3] D. Zibar, R. Sambaraju, A. C. Jambrina, J. Herrera, and I. T. Monroy, “Carrier recovery and equalization for photonic-wireless links with capac- ities up to 40 Gb/s in 75-110 GHz Band,” Opt. Fiber Conf. (OFC 2011), Los Angeles, USA, OThJ4, March 2011. [4] M. Weiss, A. St¨ ohr, F. Lecoche, and B. Charbonnier, “27 Gbit/s Photonic Wireless 60 GHz Transmission System using 16-QAM OFDM,” IEEE Intl. Topic. Meeting Microw. Photon. (MWP2009), Valencia, Spain, Post Deadline, Oct. 2009. c  IEICE 2011 DOI: 10.1587/elex.8.612 Received March 22, 2011 Accepted March 31, 2011 Published April 25, 2011 612