High-performance mid-infrared laser diodes pave the way for low-cost optical sensor development

[ Instrument Network Instrument R & D ] For the first time, researchers have directly manufactured a high-performance mid-infrared laser diode on a microelectronic-compatible silicon substrate. This new type of laser can be widely used to develop low-cost sensors for real-time, accurate environmental sensing in applications such as air pollution monitoring, food safety analysis, and pipeline leak detection.

"Most optochemical sensors are based on the interaction between molecules of interest and mid-infrared light," said Eric Tournié, team leader at the University of Montpellier, France. Manufacturing mid-infrared lasers on silicon compatible with microelectronics can significantly reduce costs because they can be manufactured using the same high-capacity processing technology used to make silicon microelectronics for cell phones and computer power. "

This new manufacturing method was performed in a high-impact study in Optica (Journal of Optical Association (OSA)). This work is being done under additional facilities and as part of the Cardinal Alliance, which is developing small, portable, low-cost optical sensors for portable gas and liquid chemical detection.

"In this project, we are working upstream by developing photonic devices for future sensors. At a later stage, these new mid-infrared lasers can be combined with silicon photonic components to create intelligent integrated photons," said Tunney. sensor."

Industry compatible manufacturing

Laser diodes are made of semiconductor materials and convert electricity into light. Mid-infrared light can be generated using a semiconductor called III-V. For about a decade, researchers have been working to deposit III-V semiconductor materials on silicon using a method called epitaxy.

Although researchers previously demonstrated lasers on silicon substrates, these substrates did not meet industry standards for microelectronics manufacturing. When industrially compatible silicon is used, differences in the structure of silicon and III-V semiconductor materials can cause defects to form.

"A special defect called inverse phase boundary is a device killer because it can cause short circuits. In this new work, we have developed an epitaxial method to prevent these defects from reaching the device's section."

Researchers have also improved the process of making laser diodes from epitaxial materials. As a result, they were able to fabricate a complete laser structure with a single epitaxial tool on an industrially compatible silicon substrate.

High-performance laser

Researchers have demonstrated this new method by producing mid-infrared laser diodes that operate in continuous wave mode and have low optical losses. They now plan to study the life of the new equipment and the relationship between that life and the manufacturing and operating modes of the equipment.

They say that once their method is fully mature, using silicon microelectronic tools to epitaxial lasers on large silicon substrates (up to 300 mm in diameter) will improve control of the manufacturing process. This, in turn, will further reduce laser manufacturing costs and enable the design of new devices. This new laser can also be combined with passive silicon photonics integrated circuits or CMOS technology to make small, low-cost, high-sensitivity smart photon sensors for gas and liquid measurement.

"The semiconductor materials we use can make lasers or photodetectors that operate in a wide spectral range from 1.5 microns (telecommunications band) to 25 microns (far infrared). Our manufacturing methods can be applied to any silicon platform The field of integrated III-V semiconductors. For example, we have used this new epitaxial method to make 8-micron quantum cascade lasers. "