Interleaved Silicon Nitride AWG Spectrometers

Interleaved arrayed waveguide gratings (AWGs) have a great potential in providing large channel counts and narrower channel spacings for many applications, including optical communication, spectroscopy, and imaging. Here, a 75-channel silicon nitride-based interleaved AWG was experimentally demonstrated. The design is comprised of a 3-channel primary AWG with 1 nm of resolution and three 25-channel secondary AWGs each with 3 nm of resolution. The final device has a spectral resolution of 1 nm over 75-nm bandwidth centered at 1550 nm. Its performance is compared with a conventional AWG spectrometer with 75 nm of bandwidth and 1 nm of resolution. The interleaved AWG demultiplexer showed lower crosstalk and better uniformity in addition to being two times smaller than the conventional design.