A Linearization Analog Photonic Link With High Third-Order Intermodulation Distortion Suppression Based on Dual-Parallel Mach–Zehnder Modulator

A scheme to realize a high linear analog photonic link based on a dual-parallel Mach–Zehnder modulator (DPMZM) is proposed and demonstrated in this paper. By using only two electrical phase shifters with
$\pi$
phase shift and optimizing the biases of the DPMZM, the third-order intermodulation distortion (IMD3) is completely eliminated by taking all the sidebands in the optical spectrum that produce IMD3 into consideration in theory. Without digital linearization, other optical processers, and symmetrical single-sideband modulation, optical carrier suppression (OCS) is achieved in one of the submodulators of DPMZM, which guarantees the effectiveness of information transmission. Quadrature modulation is achieved in the other submodulator of DPMZM, and the electrical signals on the two electrodes are the same, which result in a simple operation. The simulated results show that IMD3 is completely suppressed when the sinusoidal electrical signals have two tones, such as 11.9 and 12 GHz, and IMD3 is lower than the noise floor at the
$-$
120 dBm level. The simulated results show that IMD3 is lower than the noise floor with
$-$
120 dBm level, and the simulated results agree well with the theoretical prediction. In addition, IMD3 suppression of approximately 45 dB is experimentally demonstrated in this paper, and the spurious-free dynamic range is improved by
$11.2\ \hbox{dB}\cdot\hbox{Hz}^{2/3} $
. The scheme could simplify the design of a high linearized analog photonic link and make it stable.