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Mar 4 2022

At the lasing threshold: GeSn alloys as a gain medium for silicon-based lasers


March 4, 2022

11:00 AM - 12:15 PM


Lecture Center D1


1140 S. Morgan St., Chicago, IL 60607

At the lasing threshold: GeSn alloys as a gain medium for silicon-based lasers

Presenter: Jay Mathews, University of Dayton


Silicon is the basis for a multi-billion dollar industry, but its optical properties have limited its use in optoelectronics for infrared (IR) applications. Many IR devices are currently made using III-V or II-VI materials, which has served to fill the gap. However, these materials tend to be expensive, and integrating the materials and devices into Si fabrication can be difficult. There are a number of applications that could benefit from Si-integrated photonics including photovoltaics, infrared detection and imaging, optical interconnects (OICs), and photonic integrated circuits (PICs). In particular, OICs and PICs require efficient laser sources, modulators, low loss waveguides, optical switches, and photodetectors, all of which must be integrated into a single Si chip using complementary metal-oxide-semiconductor (CMOS) processing.
The biggest gap in technology at the moment is the development of an on-chip light source. One possible solution is to use GeSn alloys as a gain medium for laser devices. These thin films are grown on Si substrates and compatible with standard Si processing techniques, they have band gaps in the infrared, and the band structure of GeSn yields more efficient optical absorption and emission than that in Si. These unique properties have prompted a recent effort to develop optoelectronics from GeSn films, and this research has resulted in a number of prototype photonic devices such as photodetectors that cover all telecommunications wavelengths, infrared light-emitting diodes, and optically-pumped waveguide lasers. However, GeSn waveguide devices have only demonstrated lasing at cryogenic temperatures.
Mathews will present recent work on the fabrication and characterization of waveguide devices made from GeSn alloys and subjected to optical pumping at room temperature. Based on these results, an emission model was developed to predict the optical emission characteristics based on the material properties, waveguide geometry, and experimental conditions. The model was used to explain the emission data from the GeSn waveguides, and it was compared to other recent GeSn waveguide experiments. He will present details of the modeling, along with some predictions on how room temperature lasing could be achieved.

Speaker bio:

Jay Mathews is an associate professor in the Department of Physics and the Department of Electro-Optics and Photonics at the University of Dayton. He obtained his BS with double major in physics and mathematics from Colorado State University in 2007, and received his PhD in physics from Arizona State University in 2011. Following graduation, he was awarded a fellowship in the National Academy of Sciences Research Associateship Program, where he performed research for the US Army’s Benet Laboratories at Watervliet Arsenal in New York until July 2013. He joined the physics department at UD in 2013. Mathews’ research is focused on photonic materials and devices. Since starting at UD, he has been awarded ~$1M in internal and external research funding. He also serves as the chair elect of the Ohio Region Section of the American Physical Society (OSAPS). Mathews received an Air Force Office of Scientific Research Young Investigator Award in 2016, and he received the 2019 Diversity and Inclusion Advocacy Recognition prize from Optica (formerly OSA).

Faculty Host: Thomas A. Searles,

This lecture will not be recorded. 


ECE Student Affairs

Date posted

Mar 4, 2022

Date updated

Mar 4, 2022