Fiber Gratings:

Turan Erdogan, The Institute of Optics, University of Rochester

An exciting recent development in fiber-optic technology is the ability to holographically imprint diffraction gratings into the core of an optical fiber using intense UV light.
Today the most important communications application for fiber gratings is passive filtering for WDM management, including channel demultiplexing. Near-term applications include in-span signal management (e.g., channel add-drop filters) and signal conditioning (e.g. gain flattening and dispersion management).