Bit-sliced, ultra-compact slow-light Mach-Zehnder modulator for low-power operation at 6-bit resolution

This paper presents a compact, slow-light-enhanced segmented Mach-Zehnder modulator (MZM) designed for power-efficient photonic computing systems. By leveraging an apodized Bragg grating to induce slow-light effects, we achieve a total phase-shifter length of only 200 µm. The device operates as an electro-optic digital-to-analog converter (eoDAC) using two cascaded 3-bit segments to achieve 6-bit resolution, shifting bit weighting into the optical domain via the segment length ratio to bypass the exponential power scaling of high-resolution electronic DACs. The modulator achieves a normalized mean square error (NMSE) of <10^-2 at clock rates up to 1 GHz and a power reduction of approximately 15%. This architecture provides a scalable, high-precision solution for dense, high-throughput silicon photonic accelerators in machine learning applications.