We have proposed and demonstrated a double-pass ytterbium-doped fiber amplifier using an optical circulator and a fiber Bragg grating as reflector. When the signal has passed through the ytterbium-doped fiber once, it reflects off a 0.2-nm passive fiber Bragg grating filter. This reduces amplified spontaneous emission (ASE) noise from the first pass. The input signal light is amplified both forward and backward through ytterbium-doped fiber. With this double-pass configuration, 1053.15-nm unsaturated signal gain of 28 dB, gain coefficient of 1.1 dB/mW, and noise figure of less than 4 dB are achieved at 977-nm pump power of 68 mW. It is also found that this double-pass configure provides enhancing gain coefficient and improving noise figure by comparison with single-pass configuration.
© 2005 Chinese Optics Letters
(050.2770) Diffraction and gratings : Gratings
(060.2320) Fiber optics and optical communications : Fiber optics amplifiers and oscillators
(140.4480) Lasers and laser optics : Optical amplifiers
Anting Wang, Meishu Xing, Guanghui Chen, Wenkui Yang, Hai Ming, Jianping Xie, and Yunxia Wu, "Double-pass ytterbium-doped fiber amplifier with high gain coefficient and low noise figure," Chin. Opt. Lett. 1, 532-534 (2003)