Enhanced optical four-wave-mixing in integrated ring resonators with
graphene oxide films
Abstract
Layered two-dimensional (2D) graphene oxide (GO) films are integrated
with micro-ring resonators (MRRs) to experimentally demonstrate enhanced
nonlinear optics in the form of four-wave mixing (FWM). Both uniformly
coated and patterned GO films are integrated on CMOS-compatible doped
silica MRRs using a large-area, transfer-free, layer-by-layer GO coating
method together with photolithography and lift-off processes, yielding
precise control of the film thickness, placement, and coating length.
The high Kerr nonlinearity and low loss of the GO films combined with
the strong light-matter interaction within the MRRs results in a
significant improvement in the FWM efficiency in the hybrid MRRs.
Detailed FWM measurements are performed at different pump powers and
resonant wavelengths for the uniformly coated MRRs with 1−5 layers of GO
as well as the patterned devices with 10−50 layers of GO. The
experimental results show good agreement with theory, achieving up to
~7.6-dB enhancement in the FWM conversion efficiency
(CE) for an MRR uniformly coated with 1 layer of GO and
~10.3-dB for a patterned device with 50 layers of GO. By
fitting the measured CE as a function of pump power for devices with
different numbers of GO layers, we also extract the dependence of GO’s
third-order nonlinearity on layer number and pump power, revealing
interesting physical insights about the evolution of the layered GO
films from 2D monolayers to quasi bulk-like behavior. These results
confirm the high nonlinear optical performance of integrated photonic
resonators incorporated with 2D layered GO films.