Lithium niobate (LN) has been the material of choice for electro-optic modulation due to its wide optical transparency (0.35–4.5 μm), large electro-optic coefficients (r33 = 30 pm/V), which are preserved at elevated temperatures due to its high Curie temperature (~1200°C), and excellent chemical and mechanical stability resulting in long-term material reliability. However, combining this attractive material platform with plasmonics is largely unexplored. Here, we demonstrate monolithic and compact plasmonic modulators based on the Pockels effects in LN, where the metal electrodes utilized for applying a RF electric field inherently supports the propagation of the modulated surface plasmon polariton modes. Extreme confinement and good spatial overlap of both slow-plasmon modes and electrostatic fields allow us to demonstrate record high electro-optic efficiencies for modulator devices based on LN
Metasurface studies have demonstrated vast applications to control optical properties of light based on the ability to design unit cells with desired phase and reflectivity in 2D subwavelength periodic arrays. The simplified design strategy is only an approximation since the unit cells can be subject to near-field coupling effects due to influence from neighbor unit cells. In this work, we try to investigate this effect by numerically and experimentally studying the near-field response from gold nanobricks of varied length, fabricated in both quasi-periodic and periodic configuration on top of dielectric-coated (SiO2) layer and gold layer at telecommunication wavelength (1500 nm), which is the commonly used gap plasmon configuration for efficient metasurfaces. The experimental near-field investigation is performed using a phase-resolved scattering-type scanning near-field optical microscopy (s-SNOM) in the transmission mode. We demonstrate that near-field coupling becomes significant when edge-to-edge separation between GSP elements goes below ~200-250 nm. We also show that the reflection phase of any GSP element is approximately equal to its doubled near-field phase. Thus, our studies provide a direct explanation of a reduced performance of a densely-packed GSP metasurfaces. This technique can accurately predict the performance of different types of metasurfaces by observing their near-field response in different periodic configurations by considering factors ignored in the design stage, which include fabrication uncertainties, wrong design considerations along with near-field coupling effects.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.