Ultra-Broadband and Wide Field-Of-View Enhanced Polarimetric Infrared Detection Using a Plasmonic Gold Structure

Mid-wave and long-wave infrared bands become crucial for imaging and detection devices because they give unique characteristics of different objects, materials, and surfaces. Enhancing optical absorption through plasmonics is the key issue to increase the responsivity of such detection devices. Also, adding polarimetric detection to such devices can discriminate different polarizations and thus highlights and distinguishes between different features in a scene using unique signatures of different objects. In this work, a plasmonic-enhanced detection together with polarimetric discrimination is demonstrated. It covers an ultra-broadband wavelength range (3-14µm) of both mid-wave and long-wave infrared spectral bands. It is built around a focal-plane array of periodic and interleaved graded width gold-stripes and air-gaps that are placed on top of an infrared detector. A micro-bolometer is chosen as one example of infrared detection devices to evaluate the gold structure performance. The interleaved graded width structure allows covering the ultra-broadband infrared range. While the plasmonics allows having a polarization extinction-ratio discrimination up to 35dB, in addition to enhanced absorption up to 200%. Moreover, the structure allows for a wide field-of-view angle equals to 120°.