Mid-infrared GeSn Electro-Absorption Optical Modulators on Silicon

TL;DR

This paper demonstrates a monolithically integrated GeSn electro-absorption modulator on silicon that operates in the mid-infrared range, enabling scalable silicon photonics applications like communication and sensing.

Contribution

It introduces a novel GeSn-based mid-infrared optical modulator integrated on silicon, leveraging alloying to achieve effective modulation in the 2067-2208 nm range.

Findings

Achieved a maximum absorption ratio of 1.8 in the mid-infrared range.

Demonstrated clear Franz-Keldysh effect in GeSn alloy.

Device is compatible with standard CMOS manufacturing.

Abstract

Mid-infrared silicon photonics has recently emerged as a new technology for a wide range of applications such as optical communication, lidar, and bio-sensing. One key component enabling this technology is the mid-infrared optical modulator used for encoding optical signals. Here, we present a GeSn electro-absorption modulator that can operate in the mid-infrared range. Importantly, this device is monolithically integrated on a silicon substrate, which provides compatibility with standard complementary metal-oxide-semiconductor technology for scalable manufacturing. By alloying Ge with Sn to engineer the bandgap, we observed a clear Franz-Keldysh effect and achieved optimal modulation in the mid-infrared range of 2067-2208 nm with a maximum absorption ratio of 1.8. The results on the Si-based mid-infrared optical modulator open a new avenue for next-generation mid-infrared silicon photonics.