Photonic Generation of a Phase-Coded Microwave Waveform With Ultrawide Frequency Tunable Range

摘要

Photonic generation of a phase-coded microwave waveform with ultrawide frequency tunable range using two polarization modulators (PolMs) is proposed and experimentally demonstrated. The first PolM (PolM1) is used to control the polarization direction of a linearly polarized light wave to have an angle of 45$^{circ}$ or 135 $^{circ}$ relative to one principal axis of the second PolM (PolM2). PolM2 operates in conjunction with a polarization controller and a polarizer as an equivalent Mach–Zehnder modulator (MZM). Depending on the polarization direction of the incident light wave, the equivalent MZM is biased at the opposite slopes of the transfer function. Thus, by applying a binary coding signal with a switching voltage of $V_{pi}$ to PolM1, a $pi$ phase-coded microwave waveform is generated. The key significance of the technique is that a phase-coded microwave waveform with an ultrawide frequency tunable range can be generated. The technique is experimentally evaluated. The generation of a frequency-tunable phase-coded microwave waveform with a frequency at 10, 20, 30, and 40 GHz is demonstrated.