WDM Amplification of 30+30 OAM Modes in Dual Concentric Core Erbium-doped Photonic Crystal fiber Amplifier

For scaling the transmission capacity of fiber communication systems, the development of fiber and fiber amplifiers based on orbital angular momentum (OAM) modes is attractive. We propose a novel fiber design of dual concentric core photonic crystal fiber (DCC-PCF) that supports 30 OAM modes (up to ℓ = 8) in each core with adequate inter-core power isolation. All the transmitted modes have effective mode areas greater than 110 μm² and non-linear coefficients less than 1.2 W^-1 km^-1 For WDM-OAM amplification, we have considered 13 wavelength channels from 1530 nm to 1590 nm and 30+30 OAM modes, making the total number of signal channels required to be amplified 780. The gain performance of the proposed design has been extensively analyzed through numerical simulations, considering various pump configurations and design parameter variations. With the cladding pump configuration that multiplexes both the 980 nm and 1480 nm pump wavelengths, we achieve intra-core DMG of less than 0.5 dB and overall DMG of less than 2 dB. The proposed WDM-OAM-EDFA will play a crucial role in relay amplification in long-haul communication systems.