  The data communications industry has begun transitioning from electrical to
optical interconnects in datacenters in order to overcome performance
bottlenecks and meet consumer needs. To mitigate the costs associated with this
change and achieve performance for 5G and beyond, it is crucial to explore
advanced photonic devices that can enable high-bandwidth interconnects via
wavelength-division multiplexing (WDM) in photonic integrated circuits.
Subwavelength grating (SWG) filters have shown great promise for WDM
applications. However, the small feature sizes necessary to implement these
structures have prohibited them from penetrating into industrial applications.
To explore the manufacturability and performance of SWG filters in an
industrial setting, we fabricate and characterize O-band subwavelength grating
filters using the monolithic photonics technology at GLOBALFOUNDRIES (GF). We
demonstrate a low drop channel loss of -1.2 dB with a flat-top response, a high
extinction ratio of -30 dB, a 3 dB channel width of 5 nm and single-source
thermal tunability without shape distortion. This filter structure was designed
using elements from the product design kit provided by GF and functions in a
compact footprint of 0.002 mm2 with a minimum feature size of 150 nm.
