Title :
Tunable flat lenses in the infrared
Author :
Pugh, Jonathan R. ; Stokes, Jamie L. ; Lopez-Garcia, Martin ; Gan, Choon-How ; Nash, Geoff R. ; Rarity, J.G. ; Cryan, Martin J.
Author_Institution :
Dept. of Electr. & Electron. Eng., Univ. of Bristol, Bristol, UK
Abstract :
We present a beam focusing flat lens for use in the mid-infrared wavelength range. An aperture and second-order grating structure in thin gold and silicon layers is used to excite and then scatter a propagating surface plasmon polariton (SPP) to constructively interfere in the far-field to produce a narrow beam. The silicon layer acts as a mechanism for enhancing the surface plasmon polariton coupling efficiency and as a material whose refractive index can be increased by heating. We have shown through heating the silicon layer to 900 °C, we can tune the beaming angle of the lens through -7° to 7°.
Keywords :
diffraction gratings; elemental semiconductors; gold; lenses; metallic thin films; optical focusing; optical tuning; polaritons; refractive index; semiconductor thin films; silicon; surface plasmons; Au; Si; aperture; beam focusing; beaming angle; coupling efficiency; mid-infrared wavelength range; propagating surface plasmon polariton; refractive index; second-order grating structure; temperature 900 degC; thin gold layers; thin silicon layers; tunable flat lenses; Apertures; Couplings; Gratings; Laser beams; Plasmons; Silicon; Surface waves; beam-steering; finite-difference time-domain (FDTD) modeling; flat-lens; infrared; plasmonics;
Conference_Titel :
Transparent Optical Networks (ICTON), 2014 16th International Conference on
Conference_Location :
Graz
DOI :
10.1109/ICTON.2014.6876715
