Browsing by Subject "Electric field intensities"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Enhanced tunability of V-shaped plasmonic structures using ionic liquid gating and graphene
    (Elsevier Ltd, 2016) Ozdemir, O.; Aygar, A. M.; Balci, O.; Kocabas, C.; Caglayan, H.; Özbay, Ekmel
    Graphene is a strong candidate for active optoelectronic devices because of its electrostatically tunable optical response. Current substrate back-gating methods are unable to sustain high fields through graphene unless a high gate voltage is applied. In order to solve this problem, ionic liquid gating is used which allows substrate front side gating, thus eliminating the major loss factors such as a dielectric layer and a thick substrate layer. On the other hand, due to its two dimensional nature, graphene interacts weakly with light and this interaction limits its efficiency in optoelectronic devices. However, V-shaped plasmonic antennas can be used to enhance the incident electric field intensity and confine the electric field near graphene thus allowing further interaction with graphene. Combining V-shaped nanoantennas with the tunable response of graphene, the operation wavelength of the devices that utilize V-shaped antennas can be tuned in situ. In the present paper, we demonstrate a graphene-based device with ionic liquid gating and V- shaped plasmonic antennas to both enhance and more effectively tune the total optical response. We are able to tune the transmission response of the device for up to 389 nm by changing the gate voltage by 3.8 V in the mid-infrared regime.
  • Thumbnail Image
    ItemOpen Access
    Perfectly absorbing ultra thin interference coatings for hydrogen sensing
    (OSA - The Optical Society, 2016) Serhatlioglu, M.; Ayas S.; Bıyıklı, Necmi; Dana, A.; Solmaz, M. E.
    Here we numerically demonstrate a straightforward method for optical detection of hydrogen gas by means of absorption reduction and colorimetric indication. A perfectly absorbing metal-insulator-metal (MIM) thin film interference structure is constructed using a silver metal back reflector, silicon dioxide insulator, and palladium as the upper metal layer and hydrogen catalyst. The thickness of silicon dioxide allows the maximizing of the electric field intensity at the Air/SiO2 interface at the quarter wavelengths and enabling perfect absorption with the help of highly absorptive palladium thin film (∼7 nm). While the exposure of the MIM structure to H2 moderately increases reflection, the relative intensity contrast due to formation of metal hydride is extensive. By modifying the insulator film thickness and hence the spectral absorption, the color is tuned and eye-visible results are obtained.
  • Thumbnail Image
    ItemOpen Access
    Phase retrieval from electric field intensity for wide angle optical fields
    (OSA, 2017) Külçe, Onur; Onural, Levent
    An intensity preserving scalar to vector electric field mapping, in a wave propagation environment, based on a filtering procedure is proposed. In a phase retrieval problem, the proposed mapping outperforms the conventional mapping.