  We propose and demonstrate subwavelength grating (SWG) metamaterial
waveguides and ring resonators on a silicon nitride platform for the first
time. The SWG waveguide is engineered such that a large overlap of 53% of the
Bloch mode with the top cladding material is achieved, demonstrating excellent
potential for applications in evanescent field sensing and light amplification.
The devices, which have critical dimensions greater than 100 nm, are fabricated
using a commercial rapid turn-around silicon nitride prototyping foundry
process using electron beam lithography. Experimental characterization of the
fabricated device reveals excellent ring resonator internal quality factor
(2.11x10^5) and low propagation loss (~1.5 dB/cm) in the C-band, a significant
improvement of both parameters compared to silicon based SWG ring resonators.
These results demonstrate the promising prospects of SWG metamaterial
structures for silicon nitride based photonic integrated circuits.
