Gain flattened, wideband erbium doped fiber amplifiers

A flattened gain spectrum in an erbium doped fiber amplifier (EDFA) in the third telecommunication window is important for the future development of wavelength division multiplexed (WDM) long-haul optical fiber communication systems.; The bandwidth of an EDFA is typically 3-8nm, but it can be increased to more than 30nm with appropriate gain-flattening. This is done by using an optical filter to selectively couple out the peak radiation band of the erbium doped fiber, thereby reducing the peak gain. The main limitation to the performance of an EDFA without an optical filter, is the buildup of the amplified spontaneous emission (ASE) at the peak gain band. By introducing the optical filter within the EDFA, the ASE is reduced at the peak wavelength band and increased gain seen at longer wavelengths can be obtained. This also improves the noise figure of the EDFA.; This thesis reports on the experimental and theoretical studies performed to obtain a flattened gain spectrum in the EDFA. A new EDFA configuration, where an optical Bragg fiber filter in inserted at the center of the erbium doped fiber, is proposed. The gain and noise figure of this gain flattened EDFA are investigated both experimentally and through computer modeling. The results show that wideband gain flattening can be achieved in the EDFA by introducing a single angled Bragg fiber filter.