摘要
As the bottleneck device of a space-division multiplexing(SDM)communication system that exploits the degrees of freedom to further increase the capacity within the transmission band,the main challenge facing the integrated SDM amplifier is how to increase the number of amplified modes and reduce the difference in mode gain to increase the total transmission capacity and satisfy the performance specifications required by the system.Here,a cladding-pumped five-orbital-angular-momentum(OAM)-mode-group erbium-doped fiber amplifier(5MG-EDFA)based on a center-raised ring-core erbium-doped fiber(CRC-EDF)is demonstrated,which enables parallel amplification of 20 spatial OAM mode channels with a maximum differential mode gain below 0.8 d B.The CRC-EDF with an optimized layer erbium-ion doping distribution and a high numerical aperture has a center-raised ring-core refractive index profile that supports amplification matching of five OAM mode groups,from first to fifth order,to a transmission fiber,without introducing significant crosstalk.With a single multimode pump diode,the integrated 5MG-EDFA delivers gains of more than 25 d B for each mode covering the C-band and noise figures of less than 6 d B for each mode gain.This CRC-EDF-based EDFA supporting fivemode-group amplification in a mode-division multiplexing transmission system is reported for the first time,to our knowledge,laying a foundation for long-distance,multimode communication.
基金
National Key Research and Development Program of China(2024YFB2908102)
Science and Technology Planning Project of Guangdong Province(2024B0101030001)
National Natural Science Foundation of China(U22B2010,62035018,U2001601)。
