Wideband and Dispersion Immune Microwave Photonic Phase Shifter With Tunable Optical Carrier to Sideband Ratio

A wideband microwave photonic phase shifter (MPPS) based on a dual-polarization dual-parallel Mach-Zehnder modulator (DP-DPMZM) is proposed and experimentally demonstrated. The proposed system has the features of chromatic dispersion (CD) immunity and tunable optical carrier to sideband ratio (OCSR), which can realize long fiber transmission distance with improved power efficiency. It is realized by carrier suppress double sideband (CS-DSB) plus optical carrier (OC) modulation at two orthogonal polarization states. The phases of output RF signals can be tuned continuously and independently by controlling the phases of the OCs. The experiment results show that the continuous 360° phase shifts of output RF signal over 5-25 GHz are both realized in the cases of back-to-back and fiber transmission. No CD-induced power fading and phase severe shaking of the RF signals appear after the dispersion compensating fiber (DCF) of -331 ps/nm at 1545 nm transmission. By optimizing the OCSR of the system, the output RF power efficiency of the proposed scheme realizes significantly improvement when input RF powers and output optical powers are both fixed. The possibility of generating frequency doubling signal is also verified.