Band-rejection fiber filter using periodic core deformation

Summary form only given. Recently an alternate method of making long-period gratings based on periodic deformation of the fiber core using a CO₂ laser was introduced: for conversion of the LP₀₀ to the LP₁₁ mode in dispersion-compensation applications. In this paper we extend the above method to fabricate gratings, which act as spectrally selective loss elements. High effective index changes induced by this method allow high conversion efficiencies with smaller number of periods, resulting in shorter device lengths. The devices are easy to package and less sensitive to externally induced bends, temperature, and strain.