Abstract
Enhanced supercontinuum generation (SCG) is experimentally demonstrated
in integrated silicon nitride (Si3N4) waveguides incorporating highly
nonlinear graphene oxide (GO) in the form of two-dimensional (2D) films.
On-chip integration of the 2D GO films with precise control of their
thickness is realized by using a transfer-free and layer-by-layer
coating method. The control of the film length and coating position is
achieved via window opening in the upper silica cladding of the photonic
integrated chips. Detailed SCG measurements are performed using the
fabricated devices with different waveguide geometries and GO film
thicknesses, and the results are compared with devices without GO.
Significantly improved spectral broadening of ultrashort optical pulses
with ultrahigh peaks powers exceeding 1000 W is observed for the hybrid
devices, achieving up to 2.4 times improvement in the spectral bandwidth
relative to devices without GO. Theoretical analyses for the influence
of GO film thickness, coating length, coating position, and waveguide
geometry are also provided by fitting the experimental results with
theory, showing that there is still significant room for further
improvement. This work opens up a promising new avenue towards improving
the SCG performance of photonic integrated devices by incorporating
functional 2D materials.