Optically‐Synthesized Digital‐To‐Analog Converter Based on a Multi‐Segmental TFLN Mach‐Zehnder Modulator

ABSTRACT In this study, a photonic digital‐to‐analog (DAC) converter is proposed and experimentally demonstrated using a triple‐segment thin‐film lithium niobate (TFLN) modulator, capable of generating arbitrary 3‐bit optical waveform. The measured 3‐dB bandwidth of all three segments is larger than 43 GHz with a modulation efficiency of approximately 2.2 V/cm. The superior performance of the proposed device is further validated in the system level by generating PAM‐8 optical digitalized signal for an intensity modulation direct detection (IMDD) system and arbitrary high‐speed optical analog signal. Specifically, with the proposed photonic DAC, 120 and 180 Gb/s PAM‐8 optical signals are generated for an IMDD system, eliminating the need for high‐speed electrical DAC as in the traditional approaches. Moreover, 30, 40, and 60 GBaud triangular waves, sawtooth waves, and arbitrary waveforms are also successfully generated with the proposed device, and eight distinguishable output levels are observed. Also, the proposed structure can be scaled to more bits by employing additional segments in the MZM, finding its various applications where compact digital‐to‐analog conversion is needed.