Enhanced self-phase modulation in silicon nitride nanowires with
integrated graphene oxide 2D films
Abstract
We experimentally demonstrate enhanced self-phase modulation (SPM) in
silicon nitride (Si3N4) waveguides
integrated with 2D graphene oxide (GO) films. GO films are integrated
onto Si3N4 waveguides using a
solution-based, transfer-free coating method that enables precise
control of the film thickness. Detailed SPM measurements are carried out
using both picosecond and femtosecond optical pulses. Owing to the high
Kerr nonlinearity of GO, the hybrid waveguides show
significantly improved spectral broadening compared to the uncoated
waveguide, achieving a broadening factor of up to ~3.4
for a device with 2 layers of GO. By fitting the experimental results
with theory, we obtain an improvement in the waveguide nonlinear
parameter by a factor of up to 18.4 and a Kerr coefficient
(n2) of GO that is about 5 orders of magnitude
higher than Si3N4. Finally, we provide a
theoretical analysis for the influence of GO film length, coating
position, and its saturable absorption on the SPM performance. These
results verify the effectiveness of on-chip integrating 2D GO films to
enhance the nonlinear optical performance of
Si3N4 devices.