1. D.R. Zimmerman, L.H. Spiekman, Amplifiers for the masses: EDFA, EDWA, and SOA amplets for metro and access applications. J. Lightw. Technol. 22, 63–70 (2004)
2. R.E. Hunsperger, Optical amplifiers, chap. 13, in Integrated Optics, Springer, 6th edn. (2009), pp. 259–275
3. V. Ter-Mikirtychev, Fundamentals of Fiber Lasers and Fiber Amplifiers (Springer, 2014)
4. S. Singh, R.S. Kaler, Review on recent developments in hybrid optical amplifier for dense wavelength division multiplexed system. Opt. Eng. 54, 100901(1–11) (2015)
5. M. Singh, A review on hybrid optical amplifiers. J. Opt. Commun. 39(3), 267–272 (2018)