Low-crosstalk WDM by Bragg diffraction from thermally fixed reflection holograms in lithium niobate

Dense wavelength-division-multiplexing (WDM) systems require narrowband wav elength filters for simultaneous multiplexing/demultiplexing of several cha nnels. As a proof of concept the authors report the demultiplexing of two c hannels (channel spacing 0.8 nm) by Bragg diffraction from two thermally fi xed volume phase reflection holograms in photorefractive lithium niobate cr ystals doped with iron. More than 25 dB crosstalk suppression is achieved, and intensity losses are only between 2.3 and 5.2 dB.