Simple fiber loop optical notch filter

摘要

Abstract: A method of using a length of looped optical fiber with high cutoff wavelength as an EDFA gain equalizer has bee proposed. Such a fiber loop, with cutoff wavelength round the first EDFA gain peak (approximately 1.53 $mu@m), can act as a notch-filter by taking advantage of radiation loss, which is different from the cutoff loss of multi-mode optical fibers due to the single-mode light launching into such fiber filter, to smooth the EDFA gain spectrum.!9