[1] Huang D X, Liu D, Yu S et al.. Packaged double-pass travelling-wave semiconductor laser amplifier. Electron. Lett., 1991, 27(7):571~572
[2] Yamashita S, Okoshi T. Performance improvement and optimization of fiber amplifier with a midway isolator. IEE. Photo. Tech. Lett., 1992, 4(11):1276~1280
[4] Yohji Fujii. High-isolation polarization-independent optical circulator coupled with single-mode fibers. J. Lightwave Tech., 1991, 9(4):456~460