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Brad Jefferies
Lincoln University, Jefferson City, MO
Advisor: Dr. Sunder Balasubramanian
Abstract
Adaptive semiconductor multiple quantum wells are able to act as dynamic holographic films in interferometry. They can be used to look at vibrating surfaces and image the sound propagation in a three dimensional object. This gives a density map of the object. This project involves designing a semiconductor multiple quantum well structure and then get it grown commercially. Devices will then be fabricated and optically characterized before being used in a laser-based ultrasound detection system. A thinfilm structure has been designed with layer thicknesses determined by the device fabrication process. Simulations were done to determine ion-implantation doses to make the sample semi-insulating. This enables the sample to be biased by an electric field and the sample's non-linear optical properties that are quadratic with applied electric field allow for sensitive interferometric detection at low light intensities. The fabricated device is optically characterized on a spectrometer table as well as a laser-table. The spectrometer table has been setup and tested for signal to noise baselines using existing thinfilm devices. The device fabrication will commence once the growth comes back from the commercial grower and the same characterization tools will be used to test those devices. The devices will then be inserted into an existing laser-based ultrasound system to check their performance in ultrasound detection.
Brad Jefferies is an undergraduate physics major in the Department of Life and Physical Sciences at Lincoln University. He is interested in applied physics and engineering physics. He would like to go to graduate school after finishing his bachelors.
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