Active infrared materials for beam steering

The mid-infrared (mid-IR, 3 (micro)m -12 (micro)m) is a highly desirable spectral range for imaging and environmental sensing. We propose to develop a new class of mid-IR devices, based on plasmonic and metamaterial concepts, that are dynamically controlled by tunable semiconductor plasma resonances. It is well known that any material resonance (phonons, excitons, electron plasma) impacts dielectric properties; our primary challenge is to implement the tuning of a semiconductor plasma resonance with a voltage bias. We have demonstrated passive tuning of both plasmonic and metamaterial structures in the mid-IR using semiconductors plasmas. In the mid-IR, semiconductor carrier densities on the order of 5E17cm-3 to 2E18cm-3 are desirable for tuning effects. Gate control of carrier densities at the high end of this range is at or near the limit of what has been demonstrated in literature for transistor style devices. Combined with the fact that we are exploiting the optical properties of the device layers, rather than electrical, we are entering into interesting territory that has not been significantly explored to date.