Photonic generation of background free binary and quaternary phase coded microwave pulses based on vector sum.
A photonic microwave phase coded pulse generator is proposed and experimentally demonstrated based on the principle of vector sum. The key component of the proposed pulse generator is an integrated polarization division multiplexing Mach Zehnder modulator (PDM MZM) and a 90deg hybrid coupler. By properly setting the data sequences applied to the specially biased PDM MZM, binary and quaternary phase coded microwave pulses (PCMPs) that are free from the background signals can be generated. Since no filters and polarization adjustment are involved, the proposed pulse generator is characterized by a simple structure, low loss, flexible frequency tunability and high long term stability. The experimental results show that background free 4 Gb/s Barker and Frank PCMPs at 18 GHz and 2 Gb/s Barker and Frank PCMPs at 24 GHz are successfully generated. The calculated pulse compression ratio and peak to side lobe ratio are in good agreement with the theoretical values.
Optics express