[1] Zhang S X, Liu J F, Zeng X Y et al. A modified partitioned frequency domain equalization algorithm for 3-LP mode multiplexed systems with few mode fibers[J]. Optik, 229, 166291(2021).

[2] Pei L, Li Z Q, Wang J S et al. Review on gain equalization technology of fiber amplifier using space division multiplexing[J]. Acta Optica Sinica, 41, 0106001(2021).

[3] Sabitu R I, Khan N G, Malekmohammadi A. Mode conversion based on tilted-few-mode fiber assisted by dual arc waveguide for mode-division multiplexing system[J]. Optik, 226, 165880(2021).

[4] Zhang Z Z, Guo C, Zhang Y C et al. Gain-equalized remotely pumped few-mode fiber amplifier[J]. Acta Optica Sinica, 39, 1006004(2019).

[5] Jung Y, Alam S, Li Z et al. First demonstration and detailed characterization of a multimode amplifier for space division multiplexed transmission systems[J]. Optics Express, 19, B952-B957(2011).

[6] Jung Y, Kang Q. Sleiffer V A J M, et al. Three mode Er 3+ ring-doped fiber amplifier for mode-division multiplexed transmission[J]. Optics Express, 21, 10383-10392(2013).

[7] Jung Y, Lim E L, Kang Q et al. Cladding pumped few-mode EDFA for mode division multiplexed transmission[J]. Optics Express, 22, 29008-29013(2014).

[8] Nasiri Mahalati R, Askarov D, Kahn J M. Adaptive modal gain equalization techniques in multi-mode erbium-doped fiber amplifiers[J]. Journal of Lightwave Technology, 32, 2133-2143(2014).

[9] Zhang Z Z, Guo C, Cui L et al. All-fiber few-mode erbium-doped fiber amplifier supporting six spatial modes[J]. Chinese Optics Letters, 17, 100604(2019).

[10] Genevaux P. Simonneau C, le Cocq G, et al. Amplification of 5 modes carrying each 100 Gb/s with a few mode EDFA[C]//2015 Optical Fiber Communications Conference and Exhibition (OFC), March 22-26, 2015, Los Angeles, CA, USA., 1-3(2015).

[11] Lopez-Galmiche G, Sanjabi Eznaveh Z. Antonio-Lopez J E, et al. Few-mode erbium-doped fiber amplifier with photonic lantern for pump spatial mode control[J]. Optics Letters, 41, 2588-2591(2016).

[12] Genevaux P, Simonneau C, Le Cocq G et al. A five-mode erbium-doped fiber amplifier for mode-division multiplexing transmission[J]. Journal of Lightwave Technology, 34, 456-462(2016).

[13] Zhang Z, Guo C, Cui L et al. 21 spatial mode erbium-doped fiber amplifier for mode division multiplexing transmission[J]. Optics Letters, 43, 1550-1553(2018).

[14] Wang Y L, Zhang C, Fu S N et al. Design of elliptical-core five-mode group selective photonic lantern over the C-band[J]. Optics Express, 27, 27979-27990(2019).

[15] Yang H, Chen Z L, Liu W G et al. Recent progress in photonic lantern[J]. Laser & Optoelectronics Progress, 55, 120002(2018).

[16] Shen L, Gan L, Huo L et al. Design of highly mode group selective photonic lanterns with geometric optimization[J]. Applied Optics, 57, 7065-7069(2018).

[17] Chen J, Huang Q Q, Zhang Q W et al. Orthogonal frequency division/mode division multiplexing IM-DD multimode fiber transmission system based on photonic lanterns[J]. Acta Optica Sinica, 38, 0606008(2018).

[18] Noordegraaf D, Skovgaard P M, Nielsen M D et al. Efficient multi-mode to single-mode coupling in a photonic lantern[J]. Optics Express, 17, 1988-1994(2009).

[19] Xie Y Q, Wu B J, Wen F. Influence of refractive index perturbation on mode extinction ratio in few-mode fibers[J]. Acta Optica Sinica, 40, 2306005(2020).