Willie Padilla

Metamaterials for Single Pixel Imaging at Long Wavelengths

Speaker:Willie Padilla, Duke University

Abstract: Focal plane arrays form the foundation for the vast majority of imaging systems. However, at wavelengths of 10μm and longer, it becomes difficult, expensive, and / or impractical to form focal plane arrays for imaging. Single pixel cameras are an alternative method for imaging where cost, size or efficiency rule out use of focal plane arrays. Metamaterial spatial light modulators provide advanced functionality thus enabling single pixel cameras through multiplexed techniques. A multiplexed image is sent to a detector and the measurement is repeated a number of times – usually equal to the desired resolution. Images are encoded as the coefficients of the Hadamard matrix which provides the best possible signal to noise single pixel imaging system possible. We also explore the related S-matrix for single pixel imaging and additionally utilizes compressive sensing techniques to increase imaging frame rate. Lastly we highlight the ability of metamaterials to realize hyperspectral, polarimetric, and phase sensitive imaging.

Biosketch: Padilla has been in the metamaterials field since 2000, when he co-authored the first paper on negative index materials with Smith. Padilla is particularly well known for his work at terahertz (THz) frequencies, as well as in the area of active and dynamically controlled metamaterials. While working under a Director’s Postdoctoral Fellowship at Los Alamos National Laboratory, Padilla led efforts to demonstrate dynamic tuning of a semiconductor hybrid metamaterial by photodoping and voltage control. Both of these key experiments are now widely recognized and cited. Padilla’s lab specializes in the THz, infrared, optical and magneto-optic properties of novel materials utilizing various spectroscopic methods, including Fourier transform spectroscopy and ellipsometry. Padilla’s recent interests include tailoring the emissivity of objects with metamaterial coatings, and the use of active metamaterial arrays as components in THz and infrared imaging systems.