An approach for double-frequency signals generation and analogue transmission with high inter-modulation distortion suppression

An approach of double-frequency signal generation and analogue transmission with high inter-modulation distortion suppression was described, which can be widely used for Radio Over Fiber(ROF) system. The approach was mainly based on a Dual-Parallel Mach-Zehnder modulator (DPMZM) and two electrical phase shifters. By adjusting the three biases of the DPMZM, double-frequency signals with high inter-modulation distortion suppression were generated. On the same structure, by adjusting bias of MZM2, which is the sub-modulator of DPMZM, and controlling the electrical drive voltages on the electrodes of MZM2, an analog photonic link with high IMD3(third-order inter-modulation distortion) suppression was realized. From tests, the double-frequency signals with inter-modulation distortion suppression of approximately 30 dB and the analog photonic link with complete IMD3 suppression were validated and proved. The approach reduces the difficulty, complexity, and costs of ROF system, while increasing the stability of ROF system. Experimental results for IMD3 suppression are well matched with the analysis ones.