Optically assisted digital-to-analog converters (DACs) using Nyquist pulse sequences (NPSs) are presented and investigated. Therefore, NPSs are mathematically described and analyzed. Based on this, the operating principle of a precise optical Nyquist pulse synthesizer digital-to-analog converter (PONyDAC) is described. Possible architectures of PONyDAC are derived and compared in terms of performance and practicability. Moreover, the limits of PONyDAC systems and their superiority over classical electronic DACs are discussed. Furthermore, discrete building-block based implementations and monolithic implementations in electronic-photonic integrated circuits (EPICs) are presented. To enable a practicable monolithic integration, a shrinkage of the Mach-Zehnder modulators (MZMs) has been performed by applying forward-biased phase shifters (FB-PSs). These FB-PSs are analyzed and modeled to allow the precise and reliable design of PONyDAC systems with multiple MZMs. Finally, data conversion and data transmission experiments are carried out to demonstrate the systems functionality, quantify its performance, and prove their superiority over purely electronic DACs.