Bismuth plasmonics for extraordinary light absorption in deep sub-wavelength geometriesOptics Letters
- Imre Ozbay, Amir Ghobadi, Bayram Butun, and GONUL TURHAN-SAYAN
- received 10/15/2019; accepted 11/06/2019; posted 11/07/2019; Doc. ID 379670
- Abstract: In this letter, we demonstrate an ultra-broadband metamaterial absorber of unrivaled bandwidth (BW) using extraordinary optical response of Bismuth (Bi) metal; a material selected through our analysis methodology. Based on our theoretical model, we investigate the maximum metal-insulator-metal (MIM) cavity BW achievable by any metal with a known n-k data. We show that an ideal metal in such structures should have positive real permittivity part in the near-infrared (NIR) regime. Contrary to noble and lossy metals utilized by most research groups within the field, this requirement is satisfied only by Bi, whose data greatly adheres to the ideal material properties predicted by our analysis. A Bi nano disc based MIM resonator with an absorption above 0.9 in an ultra-broadband range of 800 nm- 90 nm is designed, fabricated, and characterized. To the best of our knowledge, this is the broadest absorption BW reported for a MIM cavity in the near infrared with its upper to lower absorption edge ratio exceeding best contenders by more than 150%. According to the findings of this paper, the use of proper materials and dimensions will lead to realization of deep sub-wavelength efficient optical devices.