Interband cascade vertical surface emitting lasers for optofluidic biochemical sensors

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The objectives of this research program is to design and demonstrate single wavelength and tunable vertical cavity surface emitting semiconductor laser (VCSEL) diodes for the mid to far infrared wavelength (IR) range (2-50 microns) and to demonstrate a pilot photonic sensing system for trace gas analysis and single molecule detection using these new sources. The availability of electrically pumped low-cost VCSELs in the mid-IR wavelength region could be a major breakthrough for laser based sensing applications. Real-time trace-level gas detection is an area of fast growth with applications in such diverse fields as medical diagnostics, process control, national security, and environmental air quality monitoring. For example in order to effectively monitor the green-house gases to control global warming, there is a strong need for a sensor system for detecting and measuring trace gases in the atmosphere, especially those released by iron and steel processes, semiconductor foundries, auto emissions and livestock in farmlands. Similarly for the medical field, sensitive detection of the breath gases has the potential of becoming a non-invasive diagnostic test of components of blood that have characteristics of specific human diseases or dysfunctions of important human organs. Mid-Infrared (MIR) laser spectroscopy is an extremely effective tool for detection of various molecular trace gases which have fundamental vibrational absorption bands from 3 microns to 10 microns. Laser based sensor systems also have inherent advantages compared to chemical detectors such as rapid data collection and analysis and non-contact approach for measurements in hazardous environments. Demonstration of the new low cost VCSEL sources which can be arranged in two dimensional arrays will help to revolutionize this market and allow for portable sensor systems.