In the TU Wien design, quantum cascade heterostructures are arrayed within concentric ring-shaped waveguides (top; diameter of outer ring is 400 microns), and can act as both sources and detectors of light on the same chip. In the specific setup tested by the lab (bottom), one of the ring structures (on the right), acting in QCL mode, sends its light through a chamber containing the gas to be analyzed. The beam is reflected by a mirror (on the left) and sent back through the chamber, to be picked up by the other ring structure, acting in detector mode. [Image: TU Wien]
Quantum cascade lasers (QCL) excel as mid-infrared light sources, a characteristic that has made them a linchpin in many environmental and industrial gas-sensing applications. But though QCLs themselves can be quite small, actually setting up a sensor system requires other elements beyond the laser, which can make it tough to design compact devices ready for field use.
A team of scientists from the Vienna University of Technology (TU Wien), Austria, now offers a concept that the group believes could make designing handheld QCL-based sensors a lot easier. The key: a clever scheme that combines the laser and the detector on a single chip less than half a millimeter across (ACS Photon., doi: 10.1021/acsphotonics.6b00603).
Comments are closed.