Gratings-based wavelength-division multiplexers (WDMs) are simpler to fabricate but generally have lagged behind thin-film filters in performance. However, a compact planar device developed by physicists at Weizmann Institute of Science in Rehovot, Israel, could improve performance of gratings-based coarse WDM filters.

The device comprises several reflection volume phase gratings, each operating independently with a specific wavelength channel. In an article published in the Oct. 1 issue of Applied Optics, the researchers described the fabrication process and application of the devices in a four-channel demultiplexer operating near 800 nm. The technology delivered high, uniform channel efficiencies, worthy spectral profile cutoffs, low crosstalk and polarization independence. Alternate configuration designs could yield devices for use in 1550-nm systems.