Advanced modulation technology is an effective way to improve the performance and bandwidth of fiber optic communication systems. Key technologies include high-order Quadrature Amplitude Modulation (QAM) modulation, multi-dimensional modulation, and other advanced modulation formats. First, we propose a novel symbol division multiplexing technology (SDM) by multiplexing/de-multiplexing of multiple quadrature amplitude modulation (QAM) symbols onto one complex constellation point which can achieve an additional 40% gain for effective data rate and system spectral efficiency.