Wavelength division multiplexers are fundamental to the functioning and performance of integrated photonic circuits, with applications ranging from optical interconnects to sensing and quantum technologies. In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i. Current solutions are limited by trade-offs between channel spacing, crosstalk, insertion. Corning's R&D scientists are constantly searching for new ways to improve wavelength division multiplexing (WDM) technology.