  Nanophotonic devices offer an unprecedented ability to concentrate light into
small volumes which can greatly increase nonlinear effects. However,
traditional plasmonic materials suffer from low damage thresholds and are not
compatible with standard semiconductor technology. Here we study the nonlinear
optical properties in the novel refractory plasmonic material titanium nitride
using the Z scan method at 1550 nm and 780 nm. We compare the extracted
nonlinear parameters for TiN with previous works on noble metals and note a
similarly large nonlinear optical response. However, TiN films have been shown
to exhibit a damage threshold up to an order of magnitude higher than gold
films of a similar thickness, while also being robust, cost-efficient, bio- and
CMOS compatible. Together, these properties make TiN a promising material for
metal-based nonlinear optics.
