[3] WINZER P J. High-spectral-efficiency optical modulation formats[J]. Journal of Lightwave Technology, 2012, 30(24): 3824-3835. doi:10.1109/JLT.2012.2212180.
[4] WILLNER A E,KHALEGHI S,CHITGARHA M R,et al. All-optical signal processing[J]. Journal of Lightwave Technology, 2014, 32(4):660-680. doi:10.1109/JLT.2013.2287219.
[5] WEBB R P,DAILEY J M,MANNING R J,et al. Phase discrimination and simultaneous frequency conversion of the orthogonal components of an optical signal by four-wave mixing in an SOA[J]. Optics Express, 2011,19(21):20015-20022.
[6] ISHIKAWA H,UETAI M,GOTO N. All-optical modulation format conversion between OOK,QPSK, and 8QAM[J]. Journal of Lightwave Technology, 2019,37(16):3925-3931. doi:10.1109/JLT.2019.2918815.
[7] KISHIKAWA H,SEDDIGHIAN P,GOTO N,et al. All optical modulation format conversion from binary to quadrature phase shift keying using delay line interferometer[C]// IEEE Photonic Society 24th Annual Meeting. Arlington,VA,USA:IEEE, 2011. doi: 10.1109/PHO.2011.6110647.
[8] MORI K,KISHIKAWA H,GOTO N. Modulation format conversion from QPSK to 16QAM using delay line interferometer and spectral shaping filter[C]// 2016 21st OptoElectronics and Communications Conference(OECC) held jointly with 2016 International Conference on Photonics in Switching(PS). Niigata,Japan:IEEE, 2016.
[9] ZHANG Banghong, ZHANG Hongyu, YU Changyuan, et al. An all-optical modulation format conversion for 8QAM based on FWM in HNLF[J]. IEEE Photonics Technology Letters, 2013,25(4):327-330. doi:10.1109/LPT.2012.2236547.
[10] TOTOVIC A R,CRNJANSKI J V,KRSTIC M Met al. An efficient semi-analytical method for modeling of traveling-wave and reflective SOAs[J]. Journal of Lightwave Technology, 2014,32(11):2106-2112. doi:10.1109/JLT.2014.2317478.
[11] LORENCES-Riesgo A,ERIKSSON T A,MAZUR M,et al. Quadrature decomposition of a 20 Gbaud 16-QAM signal into 2×4-PAM signals[C]// ECOC 2016;42nd European Conference on Optical Communication. Dusseldorf,German:VDE, 2016.
[13] XU Kehang, TANG Jun, LI Yuan, et al. Transmission performance of 112 Gb/s PDM-PAM4 signal over unrepeated Ramanamplified link[C]// 2018 Asia Communications and Photonics Conference(ACP). Hangzhou,China:IEEE, 2018:1-3. doi:10.1109/ACP.2018.8595982.
