An ultralow power athermal silicon modulator

TLDR

Silicon photonics is the leading platform for ultralow‑power wavelength‑division‑multiplexed networks, but existing components consume too much power for the femtojoule‑class links needed in high‑performance computers. The authors aim to demonstrate the first modulator that simultaneously delivers high‑speed (25 Gb/s), low‑voltage (0.5 Vpp) and highly efficient (0.9 fJ/bit) error‑free operation. The modulator achieves 25 Gb/s at 0.5 Vpp with 0.9 fJ/bit error‑free operation, a record 250 pm/V electro‑optic response ten times larger than prior devices, compensates thermal drift over 7.5 °C with only 0.24 fJ/bit additional energy, and delivers total energy below 1.03 fJ/bit, establishing a new paradigm for femtojoule‑class communications.

Abstract

Silicon photonics has emerged as the leading candidate for implementing ultralow power wavelength-division-multiplexed communication networks in high-performance computers, yet current components (lasers, modulators, filters and detectors) consume too much power for the high-speed femtojoule-class links that ultimately will be required. Here we demonstrate and characterize the first modulator to achieve simultaneous high-speed (25 Gb s(-1)), low-voltage (0.5 VPP) and efficient 0.9 fJ per bit error-free operation. This low-energy high-speed operation is enabled by a record electro-optic response, obtained in a vertical p-n junction device that at 250 pm V(-1) (30 GHz V(-1)) is up to 10 times larger than prior demonstrations. In addition, this record electro-optic response is used to compensate for thermal drift over a 7.5 °C temperature range with little additional energy consumption (0.24 fJ per bit for a total energy consumption below 1.03 J per bit). The combined results of highly efficient modulation and electro-optic thermal compensation represent a new paradigm in modulator development and a major step towards single-digit femtojoule-class communications.