Abstract
We present a single pixel terahertz (THz) imaging technique using optical photoexcitation of semiconductors to dynamically and spatially control the electromagnetic properties of a semiconductor mask to collectively form a THz spatial light modulator (SLM). By co-propagating a THz and collimated optical laser beam through a high-resistivity silicon wafer, we are able to modify the THz transmission in real-time. By further encoding a spatial pattern on the optical beam with a digital micro-mirror device (DMD), we may write masks for THz radiation. We use masks of varying complexities ranging from 63 to 1023 pixels and are able to acquire images at speeds up to 1/2 Hz. Our results demonstrate the viability of obtaining real-time and high-fidelity THz images using an optically controlled SLM with a single pixel detector.
Highlights
Terahertz (THz) radiation has great potential for imaging applications [1, 2] due to its ability to penetrate most dielectric materials and non-polar liquids
A significant limitation currently preventing wide-spread THz imaging is the absence of efficient sources and detectors operating between 0.1 and 10 THz - a band of the electromagnetic spectrum often referred to as the “THz gap” [6]
Performing THz imaging, there has been moderate progress over the past 25 years. Multielement detector schemes, both microbolometer arrays [7, 8] and electro-optic sampling with high-performance CCD cameras [9], provide accurate and real-time THz images. These imaging systems often require high powered sources and/or expensive complex detectors that lack the sensitivity of single element detectors
Summary
Terahertz (THz) radiation has great potential for imaging applications [1, 2] due to its ability to penetrate most dielectric materials and non-polar liquids. There exists great technical difficulty in feasibly performing THz imaging, there has been moderate progress over the past 25 years. Multielement detector schemes, both microbolometer arrays [7, 8] and electro-optic sampling with high-performance CCD cameras [9], provide accurate and real-time THz images. These imaging systems often require high powered sources and/or expensive complex detectors that lack the sensitivity of single element detectors. While the latter technique has the benefit of high spatial resolution and accurate imaging, major shortcomings are the long acquisition time [11] and the mechanical nature of the scanning system
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