Channel selector for WDM systems based on transmissive chirped moire fiber grating

The channel spacing of a wavelength-division multiplexing (WDM) communication systems tends to be as narrow as 100 GHz (ITU-standard). In order to select these channels, an optical device with high accurate, tunable and narrower filtering characteristics is required. For this purpose, fiber gratings (FG) have been widely used since they offer high wavelength selectivity, low insertion loss and no polarization sensitivity. A main disadvantage of FGs is that they operate in reflection mode, and therefore, they must be incorporated in an optical circulator (OC) or a Mach-Zehnder (MZ) interferometer. In this work, we overcome the above mentioned drawback. We report on the design of a novel optical fiber filter to be used as channel selector in WDM systems. The configuration of the device is as a chirped moire FG.