Monolithic light source on silicon

What is it about?

Photonic integrated circuits (PICs) have the potential to be the preferred technology for data communications , light detection and ranging (LiDAR) systems for autonomous vehicles, detection of biological molecules, 6G networks across different segments, and untold future applications in a new technological era. PIC using Si photonics (SiPh) platform have increasingly attracted attention for the past two decades. By leveraging the mature Si complementary metal–oxide–semiconductor (CMOS) technology, PIC on SiPh platform enables seamless integration of electronics and photonics components on a single chip, allowing low-cost, high-yield, and volume manufacturing. Among the photonic building blocks, including light sources, modulators, waveguides, photodetectors, etc., the main issue has been and is still the lack of high-performance light sources on Si. Research advances in all-group-IV SiGeSn semiconductors have opened a new avenue for the development of Si-based lasers. In this work, a set of GeSn MQW samples were designed, grown, and fabricated into edge-emitting lasers, with gradually increased optical confinement factor. Characterization results show a clear trend: device with smallest optical confinement factor cannot lase, while two other devices with high optical confinement factors exhibit lasing up to 90 K. The results of this work indicate a promising capability of GeSn material for Si-based laser applications.

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Photo by Alexandre Debiève on Unsplash

Photo by Alexandre Debiève on Unsplash

Why is it important?

It is well acknowledged that the monolithically integrated light sources would facilitate high-efficiency devices/systems and boost large-scale industrial manufacturing, satisfying the future long-term and high-volume markets. SiGeSn alloys are capable of two degrees of freedom in engineering the bandgap energy and lattice constant, through which the true direct bandgap was experimentally identified, followed by the report of GeSn optically pumped lasers from several research groups worldwide. With the knowledge gained from optical pumping study, the first generation electrically injected laser was successfully demonstrated using a double heterostructure. The maximum peak power was measured as 2.7 mW/facet at 10 K.

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