Browsing by Author "Turhan-Sayan, G."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Bismuth plasmonics for extraordinary light absorption in deep sub-wavelength geometries
    (OSA - The Optical Society, 2020) Özbay, İ.; Ghobadi, Amir; Bütün, Bayram; Turhan-Sayan, G.
    In this Letter, we demonstrate an ultra-broadband metamaterial absorber of unrivaled bandwidth (BW) using extraordinary optical response of bismuth (Bi), which is the material selected through our novel analysis. Based on our theoretical model, we investigate the maximum metal–insulator–metal (MIM) cavity BW, achievable by any metal with known n-k data. We show that an ideal metal in such structures should have a positive real permittivity part in the near-infrared (NIR) regime. Contrary to noble and lossy metals utilized by most research groups in the field, this requirement is satisfied only by Bi, whose data greatly adhere to the ideal material properties predicted by our analysis. A Bi nanodisc-based MIM resonator with an absorption above 0.9 in an ultra-broadband range of 800 nm–2390 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 NIR with its upper-to-lower absorption edge ratio exceeding best contenders by more than 150%. According to the findings in this Letter, the use of proper materials and dimensions will lead to realization of deep sub-wavelength efficient optical devices.
  • Thumbnail Image
    ItemOpen Access
    Broadband one way propagation via dielectric waveguides with unequal effective index
    (IEEE, 2014) Öner, B. B.; Üstün, K.; Kurt, H.; Okyay, Ali Kemal; Turhan-Sayan, G.
    We present an efficient approach for broad band one way propagation of light by parallel and unequal dielectric waveguides leading different effective phase shifts. Three dimensional numerical simulations show that 30% operating bandwidth is achieved.