Digital-To-Optical Converters (DOCs) With Improved Nonlinearity for Energy-Efficient Optical Data Transmission

Digital-to-Optical Converters (DOCs) convert digital electrical signals directly to analog optical signals, eliminating the need for Digital-to-Analog Converters (DACs) in Electro-Optic (EO) modulators, for applications in energy-efficient data communication. However, nonlinearity in DOCs degrades Symbol Error Rate (SER), power, and bandwidth. We present Engineered-Segment Length (ESL) <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$D O C$</tex> circuits that achieve strictly better trade-offs in Integral Non-Linearity (INL), Differential Non-Linearity (DNL), SER, and optical power vs. state-of-the-art DOC circuits. We experimentally demonstrate DOCs in heterogeneously integrated Si CMOS and Thin-Film Lithium Niobate (TFLN). Our measured ESL DOCs improve Root-Mean-Square (RMS) INL from 1.04 to 0.14 Least-Significant Bits (LSBs) and RMS Differential Non-Linearity (DNL) from 0.42 to 0.10 LSBs.}