Joseph Talghader
Associate Professor

B.S., 1988, EE, Rice University
M.S., 1993, EE, University of California, Berkeley
Ph.D., 1995, EE, University of California, Berkeley

Telephone: (612) 625-4524

E-mail: joey@ece.umn.edu
Web Page: http://www.ece.umn.edu/groups/opticalmems

My group works in the areas of optics and micro/nano-mechanical systems. One of our focus areas is infrared detectors. Standard uncooled detectors are designed for extreme sensitivity across the thermal infrared, but they are inappropriate for imaging high temperature regions or specific wavelength ranges. Some of our recent research has developed new ways to control the responsivity and sensing wavelengths of these detectors to accommodate these applications.

Other areas are optical coatings and heat transfer for both micro and large-scale optics. Two of the biggest challenges in optical microsystems are building devices with adequate heat conduction and integrating optical coatings that do not cause warping due to stress and thermal expansion. Some of our recent results include making stress- and thermal expansion invariant coatings and negative thermal expansion thin films for matching zero expansion glasses. These projects are leading to adaptive mirrors with high heat transfer and coatings for lightweight mirrors and high power lasers.

My group is also interested in the thermal and thermoelectric properties of contact interfaces. In microfabricated systems, the roughness of contact interfaces is often on the order of a nanometer or less, which makes their behavior much different from traditional interfaces with larger roughness. With proper design and control, micromachined interfaces may have enhanced thermoelectric properties, enabling highly efficient cooling and power generation.

A final research interest lies with microsensors. A great deal of sensor research involves creating intelligent sensors that can work in a distributed network; however, there are many applications where extremely simple sensors are more appropriate. One technology on which we are working removes all processing and communication capabilities from the sensors and uses self-assembly to read out sensor data after collection. This type of sensor is particularly well suited for fluidic systems and the first devices are being applied to metal-ion detection.


Selected Publications

Zirconium Tungstate-based Micromachined Negative Thermal Expansion Thin Films, M. S. Sutton and J. J. Talghader, Journal of Microelectromechanical Systems, Vol. 13, No. 4, August 2004.

Thermal and Mechanical Phenomena in Micromechanical Optics, J. J. Talghader, Journal of Physics D: Applied Physics, vol. 37, pp. R109-R122, 2004.

Current-controlled Curvature of Coated Micromirrors, W. Liu and J. J. Talghader, Optics Letters, vol. 28, no. 11, pp. 932-934, June 1, 2003.

Shape Control and Heat Transfer in Optical MEMS, J. J. Talghader, LEOS Newsletter (Academic Side Feature), vol. 16, no. 3, pp. 3-8, August 2002.

Thermal Contact Conductance of Actuated Interfaces, W. B. Song, M. Sutton, and J. J. Talghader, Applied Physics Letters, vol. 81, no. 7, pp. 1216-1218, August 12, 2002. Reprinted in Virtual Journal of Nanoscale Science and Technology, vol. 6, no. 8, August 19, 2002.

Adjustable Responsivity for Thermal Infrared Detectors, W. B. Song, and J. J. Talghader, Applied Physics Letters, pp. 550-552, July 15, 2002.

Thermally Invariant Dielectric Coatings for Micromirrors, W. Liu and J. J. Talghader, Applied Optics, vol. 41, no. 16, pp. 3285-3293, June 2002.

Average Optical Power Monitoring in Micromirrors, R. N. Supino and J. J. Talghader, IEEE Journal of Selected Topics in Quantum Electronics, vol. 8, no. 1, pp. 12-18, Jan/Feb 2002.

Curvature Compensation in Micromirrors with High Reflectivity Optical Coatings, K. Cao, W. Liu, and J. J. Talghader, IEEE Journal of Microelectromechanical Systems, vol. 10, no. 3, pp. 409-417, September 2001.

Electrostatic Control of Microstructure Thermal Conductivity, R. Supino and J. J. Talghader, Applied Physics Letters, vol. 78, no. 12, pp. 1778-80, 19 March 2001.