STTR PHASE I: Electro-Optic Field Sensors for Far-Infrared Imaging Applications

我们建议研究和开发一种基于超宽带电场传感器的成像系统。所提出的器件将基于一种新的光电设计，该设计能够在从近直流到几个太赫兹的频率范围内进行时域远红外光谱分析。从根本上说，电场传感器系统是基于电光晶体中的线性电光效应（波克尔效应），其中脉冲微波信号作为瞬态偏置在传感器晶体中诱导瞬态极化。然后用同步脉冲激光束探测这种偏振，激光将时空电场分布投影到CCD相机上。我们之前对这些成像传感器的研究已经证明了亚波长空间分辨率、飞秒时间分辨率、接近DC-THz带宽、亚mv /cm场灵敏度、高达100 Hz的扫描速率和优于10,000:1的信噪比。电光检测具有平坦（非谐振）的光谱响应率（从接近直流电到几个太赫兹），较大的探测器面积（1平方厘米）和扩展的动态范围（1,000,000）。检测几何结构的简单性、光学并行处理能力和出色的信噪比使该系统适用于实时、二维相干远红外成像应用。* * *

*** 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. ***