Justin Boyd Judkins

Long-period fiber gratings as band-rejection filters

Optical fiber communication systems that use optical amplifiers are increasingly seeking high-performance devices that function as spectrally-selective band-rejection filters. For example, ASE filters that improve erbium amplifier performance and band-rejection filters in Raman lasers/amplifiers1 must have low insertion losses and low back-reflections. In addition, they must be relatively inexpensive to mass-produce and should be compact after packaging. While bulk-optic filters and short-period Bragg gratings2,3 can be used for some of the applications, all the aforementioned requirements are rarely met. In this paper, we present a novel class of photoinduced, long-period fiber gratings that function as highly-efficient band-rejection filters.

All-optical switching in long-period fiber gratings

Nonlinear pulse propagation in long-period fiber gratings is studied with a mode-locked Q -switched laser pulse approximately 80ps in duration at a wavelength of 1.05 microm . Optical switching, pulse reshaping, and optical limiting are found at intensities in the range of 1-20 GW/cm(2).