Microwave Photonic Channelization Based on the Dual Vernier Effect

A microwave photonic channelization scheme based on the dual vernier effect is introduced and experimentally verified, aiming to enhance the efficiency of the wideband radio frequency (RF) channelization. The approach enables more output channels using a small number of optical frequency comb (OFC) lines. Two coherent OFCs with slightly different free spectral ranges (FSRs) enable each to act as the vernier of the other, thus forming a dual-vernier effect. A microwave photonic balanced Hartley structure is introduced in each channel to enhance image frequency rejection capability and improve channelization efficiency. Theoretical analysis shows that by using two OFCs with N comb lines, up to (4N−2) output channels can be realized. In a demonstration experiment, two OFCs with three comb lines are used, achieving 10 output channels covering the 7.1 to 13.1 GHz frequency range, with a channel bandwidth of 0.6 GHz. The image rejection ratio greater than 20 dB is achieved for all channels.