Characterization of chromatic dispersion and polarization sensitivity in fiber gratings

Fiber gratings have already become key passive components in fiber optic co mmunication systems. We have characterized gratings used in reflection for dispersion compensation and long period gratings used in transmission for g ain flattening using a low-loss, low-noise experimental setup having a pico meter optical wavelength resolution. Our measurements include reflection or transmission response, group delay and polarization dependent loss. We hav e scanned the spectrum of our devices using a very narrow linewidth tunable laser. A network analyzer is used for the chromatic dispersion measurement s, Time delays corresponding to the design values have been measured within the useful bandwidth of the gratings for dispersion compensation and the d evices have been found to have reasonably small ripples that increase in ma gnitude toward the shorter wavelength range. The long period gratings for g ain flattening have very small group delays. Polarization dependent loss ha s been measured for the first time in these devices. A polarization analyze r was used and Jones matrix analysis was applied to obtain the measurements . The gratings for dispersion compensation have small a polarization depend ent loss within their useful bandwidth, while the long period gratings exhi bit higher values and a stronger wavelength dependency in the polarization dependent loss.