Tunable gain-flattening filter using microbending long-period fiber grating

摘要

PURPOSE: A tuneable gain flattening filter of an erbium-doped fiber amplifier by using a micro bending long period fiber grating is provided to flatten a gain spectrum of an uneven optical fiber amplifier actively by controlling the central wavelength and depth of an optical absorption band with changing the grating period. CONSTITUTION: The tuneable gain flattening filter(GFF) of the erbium-doped fiber amplifier(EDFA) by using the micro bending long period fiber grating includes a few stages. In the first stage, the graphite rods(6) are arranged on a plate(7). In the second stage, the EDF(2) of the EDFA is layed on the plate(7) and micro-bending is formed on the optical core by the strain(3). In the third stage, the grating period is changed by using the angle among the graphite rods(6) and the central wavelength of the absorption band is tuned to be in accord with the wavelength large in the EDFA gain. In the fourth stage, the tuneable GFF is completed to maintain an uneven gain spectrum evenly according to the wavelength.