Electro-optic modulation in integrated photonics

TLDR

Electro‑optic modulators are essential for photonic communication, and recent advances in materials and fabrication techniques have revitalized research in optical modulation. This Perspective reviews the state of the art in integrated electro‑optic modulators across contemporary materials and platforms. The review evaluates material platforms using metrics such as extinction ratio, insertion loss, bandwidth, voltage, and footprint, introduces key electro‑optic phenomena, and discusses often‑overlooked issues like carrier density, energy consumption, and electrode design. The outlook predicts evolving research and performance trends for electro‑optic materials in the coming years.

Abstract

Electro-optic modulators are an indispensable part of photonic communication systems, largely dictating the achievable transmission rate. Recent advances in materials and fabrication/processing techniques have brought new elements and a renewed dynamic to research on optical modulation. Motivated by the new opportunities, this Perspective reviews the state of the art in integrated electro-optic modulators, covering a broad range of contemporary materials and integrated platforms. To provide a better overview of the status of current modulators, an assessment of the different material platforms is conducted on the basis of common performance metrics: extinction ratio, insertion loss, electro-optic bandwidth, driving voltage, and footprint. The main physical phenomena exploited for electro-optic modulation are first introduced, aiming to provide a self-contained reference to researchers in physics and engineering. Additionally, we take care to highlight topics that can be overlooked and require attention, such as the accurate calculation of carrier density distribution and energy consumption, the correct modeling of thin and two-dimensional materials, and the nature of contact electrodes. Finally, a future outlook for the different electro-optic materials is provided, anticipating the research and performance trends in the years to come.