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.
State engineering of photon pairs produced through dual-pump spontaneous four-wave mixing