Mid-Infrared Lasers For Sensing With Low-Cost Fabrication

High-performance mid-infrared laser diodes have been made for the first time directly on silicon substrates suitable for microelectronics. The new lasers may make the widespread creation of low-cost sensors for real-time, precise environmental sensing for air pollution tracking, food safety analysis, and pipe leak detection possible.

Most optical chemical instruments rely on the interaction of the target molecule and mid-infrared light. The expense of fabricating mid-infrared lasers on silicon compatible with microelectronics can be significantly reduced because they can be produced using the same high-volume processing methods as silicon microelectronics that power computers and mobile devices.

The study was carried out as a component of a collaboration that is creating miniaturized, transportable, affordable optical sensors for chemical detection in both liquids and gases. As part of this effort, the researchers are creating photonic devices upstream for future sensors. These novel mid-infrared lasers may eventually be combined with silicon photonics elements to produce sophisticated, integrated photonic sensors.

Although the researchers had earlier shown off lasers on silicon substrates, those substrates did not meet the requirements for fabricating microelectronics. Defects develop when III-V semiconductors and silicon with different chemical structures are used, which is industry-compatible silicon. 

Devices are killed by a specific flaw known as an anti-phase barrier because it causes short circuits. Their most recent work created an epitaxial strategy that stops these flaws from getting to a device’s active component.

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