ZTE Communications ›› 2021, Vol. 19 ›› Issue (3): 81-87.doi: 10.12142/ZTECOM.202103010

• Research Paper • Previous Articles     Next Articles

Semiconductor Optical Amplifier and Gain Chip Used in Wavelength Tunable Lasers

SATO Kenji1,2(), ZHANG Xiaobo1   

  1. 1.ZTE Photonics, Nanjing 210000, China
    2.Southeast University, Nanjing 211189, China
  • Received:2021-01-01 Online:2021-09-25 Published:2021-10-11
  • About author:SATO Kenji (zuoteng.jianer@zte.com.cn) received his B.E. degree in electrical engineering, M.E. degree in electronic engineering, and Ph.D. degree in electronic engineering from the University of Tokyo, Japan in 1991, 1993 and 1996, respectively. From 1993 to 1994, he was with the Department of Information Technology, Faculty of Applied Science, University of Ghent, Belgium, under a Flemish Government Scholarship. In 1996, he joined the Central Research Laboratories, NEC Corporation, Japan, where he had been engaged in the research and development of semiconductor laser diodes, photodetectors, modulators and silicon-photonic external cavity lasers for optical fiber communications. Since 2020, he has been a guest professor at Southeast University, China and concurrently a chip-design expert at ZTE Photonics. He is the author or coauthor of more than 60 technical and conference papers and has more than 20 registered patents.|ZHANG Xiaobo received his B.E. degree in optical engineering from Huazhong University of Science and Technology, China in 2014 and M.E. degree in optical engineering from Zhejiang University, China in 2017. In 2017, he joined ZTE Photonics, where he has been engaged in the research and development of silicon-photonic external cavity lasers for optical fiber communications.


The design concept of semiconductor optical amplifier (SOA) and gain chip used in wavelength tunable lasers (TL) is discussed in this paper. The design concept is similar to that of a conventional SOA or a laser; however, there are a few different points. An SOA in front of the tunable laser should be polarization dependent and has low optical confinement factor. To obtain wide gain bandwidth at the threshold current, the gain chip used in the tunable laser cavity should be something between SOA and fixed-wavelength laser design, while the fixed-wavelength laser has high optical confinement factor. Detailed discussion is given with basic equations and some simulation results on saturation power of the SOA and gain bandwidth of gain chip are shown.

Key words: external cavity, gain chip, saturation power, semiconductor optical amplifier, tunable laser