Treffer: Advanced digital signal processing techniques for intensity-modulated/direct-detection optical systems

Ph.D. ; Owing to the increasing demand for bandwidth and capability in various optical communication systems, many sophisticated techniques have been reported and investigated. The major target of these techniques is to realize high spectral efficiency (SE) at a relatively low cost. In fiber-optic systems, the modulated optical signal can carry data in different dimensions, including its amplitude, phase, frequency, polarization, and mode. By utilizing the information mentioned above, coherent optical systems can achieve the ultimate performance in receiver sensitivity, SE, and robustness against chromatic dispersion (CD). However, the high complexity and the high cost of coherent detection really limit its applications in some practical optical systems/networks, especially for short-reach and cost-sensitive scenarios, including passive optical network (PON), optical wireless communications (OWCs), data center network (DCN), etc. The intensity-modulated/direct-detection (IM/DD) optical system is therefore becoming a promising solution. ; Different from the coherent system, an IM/DD system can only utilize the information of intensity, leading to its lower SE and worse tolerance to various system impairments. Thus, the signal processing is usually required for supporting a higher net information rate. Compared to analog signal processing using integrated circuits, digital signal processing (DSP) techniques have the advantages of higher stability, higher feasibility, and higher cost-effectiveness, especially in the scenario of high-speed communications. With the help of advanced DSP techniques, the IM/DD optical system can address its drawbacks in several different aspects, including SE, sensitivity, security, etc., while still maintaining its advantage of low cost. This thesis investigates the design and implementation of advanced DSP techniques for IM/DD optical systems in terms of three topics. ; In the first topic, we propose two DSP algorithms for improving the transmission performance in IM/DD optical ...