Impact of dispersion on the bandwidth of long-period fiber-grating filters

Summary form only given. Long-period fiber gratings have been developed and proposed for use in numerous applications in fiber-optic communications systems. Many of these are based on the rejection filtering characteristics of these components, for which the filter bandwidth is a critical parameter. The filter spectrum can be predicted by rigorous calculations based on coupled-mode theory. But these calculations are complex, time-consuming, and do not afford much insight for design. Although simple formulas exist for estimating bandwidth these ignore the impact of fiber dispersion, which drastically alters the spectrum. In this paper we show how the bandwidth of long-period fiber-grating filters can be predicted simply and accurately. In addition, we demonstrate how fiber dispersion affects the filter characteristics more generally and introduce a simple method for taking these effects into account.