25Gb/s 1V-driving CMOS ring modulator with integrated thermal tuning

TLDR

The authors present a high‑speed ring modulator designed to meet the ideal qualities required for optical interconnects in future exascale supercomputers. The modulator, fabricated in a 130 nm SOI CMOS process with a 7.5 µm ring radius, incorporates a carrier‑depletion PN junction for high‑speed operation, a thermal tuning section providing 0.19 nm/mW wavelength adjustment, and consumes approximately 7 fJ/bit as estimated from microwave characterization and circuit modeling. It delivers 25 Gb/s modulation with an extinction ratio exceeding 5 dB using only 1 V peak‑to‑peak drive and occupies a compact 400 µm² footprint, making it suitable for exascale optical interconnects.

Abstract

We report a high-speed ring modulator that fits many of the ideal qualities for optical interconnect in future exascale supercomputers. The device was fabricated in a 130 nm SOI CMOS process, with 7.5 μm ring radius. Its high-speed section, employing PN junction that works at carrier-depletion mode, enables 25 Gb/s modulation and an extinction ratio >5 dB with only 1V peak-to-peak driving. Its thermal tuning section allows the device to work in broad wavelength range, with a tuning efficiency of 0.19 nm/mW. Based on microwave characterization and circuit modeling, the modulation energy is estimated ~7 fJ/bit. The whole device fits in a compact 400 μm2 footprint.