Coherent Microwave Photonic Links With Increased Transmission Capacity

Two microwave photonic links (MPLs) with increased transmission capacity based on coherent detection and digital signal processing are proposed. In the first MPL, two microwave vector signals at the same microwave carrier frequency are applied to a dual-drive Mach-Zehnder modulator (DD-MZM) to modulate the two signals on an optical carrier. After transmission over a single-mode fiber, the optical signal is received at a coherent receiver. To recover the two microwave vector signals, a DSP algorithm is developed. Full recovery of the microwave vector signals free from the joint phase noise between the transmitter and the local oscillator laser sources is realized. In the second MPL, the DD-MZM is replaced by a dual-parallel DD-MZM, to which four microwave vector signals are applied. Again, a DSP algorithm is developed. Full recovery of the microwave vector signals free from the joint phase noise is realized. For the MPLs, error-free transmission is experimentally demonstrated.