Modulation Frequency Characteristics of Erbium-Doped Fiber Amplifier

P. C. Becker, N.A. Olsson, J.R. Simpson

Sebastián Jarabo, Aaron Schweinsberg, N. N. Lepshkin +2 more

Weiping Zhang, P. L. Chu, Yan Xue

We analyze the sideband multiwave mixing process of an audio-frequency-modulated signal in an erbium-doped-fiber amplifier. The nearly resonant interaction of an audio-frequency-modulated signal with the doped erbium ions results in multiwave mixing, which induces the generation of new sideband frequencies. We show that the input signal is distorted by such a multiwave mixing process. The condition to reduce the distortion of an input modulated signal in an erbium-doped-fiber amplifier is evaluated.

P. C. Becker, N.A. Olsson, J.R. Simpson

Alexander William Setiawan Putra, Minoru Yamada, Hiroyuki Tsuda +1 more

Characteristics of noise in erbium doped fiber amplifier (EDFA) are theoretically analyzed and experimentally verified. Four discreet energy models are used for erbium ion transition. Spatially varying photon number for traveling optical field was defined in a spatially divided segment with finite length, whose length is decided by property of the spontaneous emission. Quantitative evaluation of the Langevin noise sources becomes possible by this model. The amplified spontaneous emission was included in terms of discrete longitudinal mode, which is defined for whole length of the EDFA. It was found that the relative intensity noise (RIN) in the EDFA hardly changes with noise frequency in the region higher than several kHz. The phase noise in EDFA also hardly changes with the noise frequency. The frequency noise of the signal light in the EDFA increases proportional to squared value of the noise frequency. The amount of RIN and the phase noise decrease in higher input optical power. Good correspondence between theoretical and experimental results was obtained.

Yoshinobu Maeda, Takao Sakakibara, M. Migitaka

The dependence of the negative nonlinear absorption effect on both modulation degree and modulation frequency of an incident laser was investigated in erbium-doped fibers at 77 K. Negative input-output characteristics were obtained at modulation frequencies of 10 to 250 kHz for fiber lengths above 2 m. The maximum ratio of the transmitted modulation degree to the incident one was approximately -2 for a fiber length of 4 m. It is suggested that emissions induced in the fiber can contribute to the negative nonlinear absorption effect because they propagate with low loss.