Quadrature-phase-shift-keying radio-over-fiber transmission for coherent optical and radio seamless networks

We propose a coherent optical and radio seamless network concept that allows broadband access without deployment of additional optical fibers within an optical fiber dead zone while enhancing network resilience to disasters. Recently developed radio-over-fiber (RoF) and digital coherent detection technologies can seamlessly convert between optical and radio signals. A millimeter-wave radio with a capacity greater than 10 Gb/s and high-speed digital signal processing is feasible for this purpose. We provide a preliminary demonstration of a high-speed, W-band (75-110 GHz) radio that is seamlessly connected to an optical RoF transmitter using a highly accurate optical modulation technique to stabilize the center frequencies of radio signals. Using a W-band digital receiver with a sensitivity of -37 dBm, we successfully transmitted an 18.6Gb/s quadrature-phase-shift-keying signal through both air and an optical fiber.