Multiband Three-Dimensional Carrierless Amplitude Phase Modulation for Short Reach Optical Communications

Abstract

Multi-dimensional carrierless amplitude phase (CAP) modulation attracts a lot interest in recent optical communications as an advanced modulation format with improved performance. In this paper, we have demonstrated a multiband three-dimensional CAP (3D-CAP) modulation scheme and investigated its applications in short reach optical communication systems. Corresponding digital filters are designed by minimax algorithm with additional linear constraint to avoid the coding intersymbol interference. The performance of the digital filters is analyzed for optical fiber links with data rate over 100 Gb/s based on simulations. Similar to discrete multitone technique, several independent bands can be loaded with different 3D-CAP signals in the proposed multiband 3D-CAP system, offering improved tolerance to non-flat channels. 2-km single mode fiber transmission at total bit rate of 112.5 Gb/s is investigated through simulations and the results indicate better performance of multiband 3D-CAP compared with conventional 3D-CAP in short reach optical communication.