Graphene oxide (GO) 2D layered films for high efficiency integrated
polarizers in ring resonators and waveguides
Abstract
Polarization selective devices, such as polarizers and polarization
selective resonant cavities (e.g., gratings and ring resonators), are
core components for polarization control in optical systems and find
wide applications in polarization-division-multiplexing, coherent
optical detection, photography, liquid crystal display, and optical
sensing. In this paper, we demonstrate integrated waveguide polarizers
and polarization-selective micro-ring resonators (MRRs) incorporated
with graphene oxide (GO). We achieve highly precise control of the
placement, thickness, and length of the GO films coated on integrated
photonic devices by using a solution-based, transfer-free, and
layer-by-layer GO coating method followed by photolithography and
lift-off processes. The latter overcomes the layer transfer fabrication
limitations of 2D materials and represent a significant advance towards
manufacturing integrated photonic devices incorporated with 2D
materials. We measure the performance of the waveguide polarizer for
different GO film thicknesses and lengths versus polarization,
wavelength, and power, achieving a very high polarization dependent loss
(PDL) of ~ 53.8 dB. For GO-coated integrated MRRs, we
achieve an 8.3-dB polarization extinction ratio between the TE and TM
resonances, with the extracted propagation loss showing good agreement
with the waveguide results. Furthermore, we present layer-by-layer
characterization of the linear optical properties of 2D layered GO
films, including detailed measurements that conclusively determine the
material loss anisotropy of the GO films as well as the relative
contribution of film loss anisotropy versus polarization-dependent mode
overlap, to the device performance. These results offer interesting
physical insights and trends of the layered GO films from monolayer to
quasi bulk like behavior and confirm the high-performance of integrated
polarization selective devices incorporated with GO films.