  Higher-order soliton dynamics, specifically soliton compression and fission,
underpin crucial applications in ultrafast optics, sensing, communications, and
signal processing. Bragg solitons exploit the strong dispersive properties of
periodic media near the photonic band edge, enabling soliton dynamics to occur
on chip-scale propagation distances and opening avenues to harness soliton
compression and fission in integrated photonic platforms. However,
implementation in CMOS-compatible platforms has been hindered by the strong
nonlinear loss that dominates the propagation of high-intensity pulses in
silicon and the low-optical nonlinearity of traditional silicon nitride. Here,
we present CMOS-compatible, on-chip Bragg solitons, with the largest
soliton-effect pulse compression to date with a factor of x5.7, along with the
first time-resolved measurements of soliton fission on a CMOS-compatible
platform. These observations were enabled by the combination of unique
cladding-modulated Bragg grating design, the high nonlinearity and negligible
nonlinear loss of compositionally engineered ultra-silicon-rich nitride (USRN:
Si7N3).

Optics