Cascaded chirped and phase-only sampled fiber Bragg gratings for efficient comb filters

Abstract

Cascaded chirped and phase-only sampled fiber Bragg gratings (CC-PSFBGs) are proposed for high efficient multi-channel comb filters in wavelength-division multiplexing (WDM) systems. A CC-PSFBG consists of replicated sections of chirped and phase-only sampled FBGs, in which the Talbot conditions for each section of phase-only sampled FBGs are satisfied. Under the condition of phase matching among the cascaded sections, an arbitrarily tunable channel spacing (tunable free spectral range, FSR) with both a controllable wavelength range and sufficient in-band energy efficiency can be implemented. It offers a useful tool for improving the design flexibility and the energy efficiency of conventional Talbot effect based multichannel comb filters.