Title:  Nanoscale Optical Devices based on Phase Coherent Electron Transport

Committee:

Dr. Paul Voss, ECE, Chair , Advisor

Dr. David Citrin, ECE

Dr. Douglas Yoder, ECE

Dr. Azad Naeemi, ECE

Dr. Nico Declercq, ME

Abstract:

The optical interaction of phase coherent electron in both ground and excited states in a material which is open (has leads) along one dimension has been investigated. It has been found that quantum interference of phase coherent electrons after optical excitation gives rise to periodic oscillation in photocurrent. This periodic oscillation results in illumination length dependent optical absorption for a material at illumination length around the Bloch wavelength of participating electrons. Under sub Bloch wavelength illumination, which has been investigated to be experimentally achievable with nanoplasmonic focusing, of a particular structure, where a gate potential has been applied in half of the device, this periodic oscillation can be utilized to manufacture new kinds of photodetectors where current in the external circuit changes direction with change in wavelength of light. This is a completely new phenomena and only possible with coherent wave-nature of electron and sub Bloch wavelength illumination. Also, the coupling of longitudinal resonant modes, which arises from phase coherent electron transport in a Mach Zehnder interferometer structure, has been investigated for manufacturing a p-n junctionless, high quantum efficiency photodetector. A new spectrometer device under coherent electron transport regime which can detect and distinguish light of different frequencies has also been discussed. A new study field called opto coherent electronics has been proposed.