The Research On Suppressing The ASE In High-power ER-Yb Codoped Fiber Amplifiers

The Er-Yb codoped fiber amplifiers (EYDFAs) are mainly applied to createhigh-power1.5-μm band laser. Due to the “eye-safe” nature,1.5-μm band laser hasgreat applications in the fields of military, communication, medicine, scientificresearches and so on. With the higher power,1.5-μm band laser can play a better role.However, the output power of high-power EYDFAs is relatively low up to now. Lotsof papers have shown that the Yb-band amplified spontaneous emission (1-1.1μm,Yb-ASE) is the main reason that limits the efficiency of high-power EYDFAs.Therefore, the main purpose of this paper is to research the situations of the Yb-ASEin high-power EYDFAs and to suppress the Yb-ASE by utilizing Yb-signal-aidedmethod.This paper has studied the high-power EYDFAs at the aspects of theory andexperiments.In theory, the theoretical model of EYDFAs is builded. The working processes ofhigh-power EYDFAs could be simulated by solving the model numerically. Bothcontinuous EYDFAs and pulsed EYDFAs with different parameters have beenresearched numerically. The results show that the Yb-ASE in counter pump directionis the major factor that limits the efficiency of continuous EYDFAs and pulsedEYDFAs. If the Yb-signal-aided method that the Yb-band signal with properwavelength and suitable power is introduced into the pump side is used, the Yb-ASEin high-power EYDFAs can be suppressed effectively and the output power of theamplifiers can also increase.In experiments, this paper mainly studies the situations of the signal and ASE inhigh-power continuous EYDFA with forward pump and the effects ofYb-signal-aided method on suppressing the Yb-ASE. The Yb-band signal is providedby the fiber Bragg grating (FBG, the center reflective wavelength is1064nm) at thesignal input side of the EYDFA, which can reflect the backward Yb-ASE. The resultsshow that with10-W pump and20-mW input signal,~2.0-W output signal is achieved.The output power of the backward Yb-ASE is stronger than the forward Yb-ASE.When added the FBG, the backward Yb-ASE is suppressed effectively, which fits thetheoretical results well. In conclusion, the counter-pump-propagating Yb-ASE mainly restricts theperformance of high-power EYDFAs. The Yb-signal-aided method can restrain theYb-ASE better and improve the efficiency of EYDFAs simultaneously.