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Will a Silicon-Based Laser Soon Be a Reality? Science is Inching Towards Goal

Image for representation.

Image for representation.

Researcher David Stark has been trying to create silicon-based quantum cascade laser (QCL).

Silicon is one of the most coveted elements in the fields of technology, engineering and even biomedical sciences.

Its versatility makes it suitable for chemical, electronic and multiple other applications with ease. As of now, the element is ubiquitous in our lives in the field of microelectronics in our phones, computers and even military equipment.

Researchers from the Institute for Quantum Electronics now believe this beautiful substance can be used to explore ways to integrate different functionalities in the form of semiconductors.

Diode lasers — like ones used in laser pointers and barcode scanners — are mostly based on gallium arsenide (GaAs). However, GaAs and silicone do not always work well together. But scientists have long wanted to realise the dream of “laser on silicon.” Professors Giacomo Scalari and Jérôme Faist from the institute may have just found a way.

Their study published in Applied Physics Letters is focused on electroluminescence. In simple terms, it is generating electrical light. The same can be achieved on silicon-germanium (SiGe), a semiconductor.

The observed emissions ranged in tera-hertz frequency band, which is a section between microwave electronics and infrared optics. The usual GaAs electrons readjust holes across the bandgap producing light but when applied in silicon, they produce heat.

Researcher David Stark has been trying to create a silicon-based quantum cascade laser (QCL). In his structure, there is no restructuring of electron-hole but they tunnel through the semiconductors’ repeated stacks. The process leads to photon emission, a unit of light energy.

Faist worked on this module in 1994 but never on silicon-based structures. He made promising predictions and has finally been able to validate his theories.

His team designed and built devices with a unit structure of SiGe and pure germanium (Ge), which were less than 100 nanometres in height, and repeated 51 times. The electroluminescence they observed matched with predictions.

While the emission is less than the GaAs-based counterpart, it is still promising. The fact that there was an emission, a proof of concept, means they are on the right track of evolving this new technology.

“The ultimate goal is to reach the room-temperature operation of a silicon-based QCL,” reported Phys.org.

It will be an evolutionary step in the field of silicon photonics; ranging from medical imaging to wireless communication.