NSF Award
9632181
*** 9632181 Stewart We propose to investigate and develop an imaging system based on ultra-wideband electric-field sensors. The proposed device will be based on a new optoelectronic design which is capable of timedomain far-infrared spectroscopy across a frequency range extending from near DC to several THz. Fundamentally, the electric-field sensor system is based on the linear electro-optic effect (Pockel's effect) in electro-optic crystals where a pulsed microwave signal acts as a transient bias to induce a transient polarization in the sensor crystal. This polarization is then probed by a synchronously pulsed laser beam, and the spatial and temporal electric-field distribution is projected onto a CCD camera by the laser. Our previous studies of these imaging sensors has demonstrated a sub-wavelength spatial resolution, femtosecond temporal resolution, near DC-THz bandwidth, sub-mV/cm field sensitivity, up to 100 Hz scan rate, and a signal-to-noise ratio better than 10,000:1. The electro-optic detection has a flat (nonresonant) spectral responsivity (from near DC to several THz), a large detector area (> 1 cm2), and an extended dynamic range (> 1,000,000). The simplicity of the detection geometry, capability for optical parallel processing, and excellent signal-to-noise ratio make this system suitable for real-time, 2-D coherent far infrared imaging applications. ***
