Optical Micro- and Nano-systems at the University of Minnesota

Joseph Talghader
Dept of Electrical and Computer Engr
University of Minnesota

One of the oldest types of optical detectors is the bolometer which was used to detect cows near the year 1900. Modern bolometers are extensively used by the military and law enforcement to detect thermal infrared (IR) light. My group is working on two MEMS (micro-electro-mechanical) technologies to extend the dynamic range of bolometers and make them wavelength tunable.

Cooled semiconductor detectors can also measure in the IR, but the ability to tune these devices is severely limited. By applying the concept of interference in optical cavities to interference in quantum well semiconductors, one may be able to create quantum structures whose bandgap is tunable in real time, making intersubband devices that can tune across all of the thermal IR.

Another area of interest for my group is optical coatings. Normally one just worries about the spectral characteristics of these coatings, but in high energy lasers and many microsystems, their mechanical properties become even more important than their optics. We have been developing negative thermal expansion thin films so that one can prevent thermal deformation under high powers. I'll discuss the physics and applications behind these strange materials.