60-GHz Transmission Link Using Uni-Traveling Carrier Photodiodes at the Transmitter and the Receiver

We present the first demonstration of a wireless transmission link based on uni-traveling carrier photodiodes (UTC-PDs) as transmitter and receiver. In this demonstration, a UTC-PD was used at the transmitter to generate a 1-Gbps on-off keying data signal at a carrier frequency of 61.3 GHz by heterodyning two modulated optical tones originating from an optical frequency comb system. The generated electrical heterodyne signal was transmitted, using a 25-dBi gain parabolic antenna. An identical antenna was used to detect the signal at the receiver, followed by an optically pumped UTC-PD mixer to down-convert the received RF signal to an intermediate frequency of 6.3 GHz, which was subsequently amplified and acquired by a real-time oscilloscope for offline processing. The recovered data showed an open eye diagram, and a bit error rate of the order of 10^-5 was measured. The receiver UTC-PD was characterized in terms of its conversion loss and noise figure (NF), and the overall NF of the receiver was measured at 21.5 dB.