  Supercontinuum generation in integrated photonic waveguides is a versatile
source of broadband light, and the generated spectrum is largely determined by
the phase-matching conditions. Here we show that quasi-phase-matching via
periodic modulations of the waveguide structure provides a useful mechanism to
control the evolution of ultrafast pulses and the supercontinuum spectrum. We
experimentally demonstrate quasi-phase-matched supercontinuum to the TE20 and
TE00 waveguide modes, which enhances the intensity of the SCG in specific
spectral regions by as much as 20 dB. We utilize higher-order
quasi-phase-matching (up to the 16th order) to enhance the intensity in
numerous locations across the spectrum. Quasi-phase-matching adds a unique
dimension to the design-space for SCG waveguides, allowing the spectrum to be
engineered for specific applications.
