Total Internal Reflection THz Devices for High Speed Imaging

Electron-hole pair photoexcitation switches a semiconductor's response from dielectric to conducting. We show that this process is most efficient in a total internal reflection (TIR) geometry allowing the use of cheaper, less powerful light sources. Further, by employing a digital micromirror device to spatially pattern the photoexcitation area, we perform imaging with single-element detector and present solutions to the optical problems of imaging in this geometry. We finally show that by taking into account the carrier lifetimes in the signal processing one can improve the acquisition rate by a factor 5.