A novel system for frequency-doubling microwave signal generation with tunable phase shift based on a dual-polarization quadrature phase shift keying (DP-QPSK) modulator which includes two dual-parallel Mach-Zehnder modulators (DPMZM) is proposed and demonstrated. The radio frequency (RF) signals drive the top DPMZM for generating a negative first-order RF sideband on the X-polarization state and drive the bottom DPMZM to obtain a positive first-order RF sideband on the Y-polarization state. After that, the two first-order sidebands enter a three wave-plates polarization controller (PC) of half-quarter-quarter (HQQ) wave plate type and then their phases are controlled. After a polarizer and a photodiode (PD), a frequency-doubling microwave or millimeter-wave signal with tunable phase shift is produced. The results indicate a full 360-degree phase shift is realized, in the meantime, the phase deviation is less than 1-degree and amplitude deviation is no more than 0.3dB.
A new microwave photonic phase shifter based on polarization modulation with capability of frequency doubling is proposed and analyzed in this paper. A +1st order sideband signal with a carrier signal and a -1st order sideband signal with a carrier signal are producted by a dual-polarization Mach-Zehnder modulator (DPol-MZM) instead of the conventional polarization modulator, which are then sent to a fiber Bragg grating (FBG) used as an optical filter to filter out 1st orthogonal sidebands signals. By adjusting the polarization direction of the polarizer and beating 1st orthogonal sidebands signals at a photodetector, a frequency-doubled microwave signal is generated and its phase is continuously tunable by tuning the polarization controller (PC2). Taking advantages of the ability of frequency doubling and using PC tune, the frequency tuning range can be wider and fully tuned over 360°. By theoretical analyses and simulated verifications, a wideband frequency-doubling microwave signal with full range phase shift is achieved.
A broadband RF photonic phase shifter that can achieve the tunable phase shift with little RF amplitude variation is presented. It is based on homodyne mixing technique. The beating between phase-modulated optical carrier and the sidebands can generate RF signal with desired phase shift. Results show the RF phase shifter can achieve a continuous phase shift with low amplitude variation.
An integrated RF photonic phase shifter that can achieve a tunable phase shift with little RF amplitude variation is presented. The beating between phase-modulated optical carrier and the first-order sideband can generate RF signal with desired phase shift. Results show the RF phase shifter can achieve a continuous 0° − 360° phase shift with low amplitude variation.