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Study On High Power Er/Yb Co-doped Fiber Amplifier

Posted on:2011-08-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:L ZhouFull Text:PDF
GTID:1118330338483215Subject:Photonics technology
Abstract/Summary:PDF Full Text Request
High power Er/Yb co-doped fiber amplifier is widely used in the areas such as: Laser radar, laser ranging, space remote sensing, environment detection, free space communication and gravity wave detection. The characteristics of the continuous wave and pulsed amplification are analyzed in theory, including the slope efficiency, gain feature, noise figure and power conversion efficiency. The appearance of the Yb ions band ASE is the dominant limit factor during the high power operation.The suppression of the Stimulated Brillouin Scatter must be considered. The model that based on the transient rate equations and Stimulated Brillouin Scatter power transmission equations is proposed for the first time, including the energy transferred from signal to the Stokes wave and the Stokes wave amplified by the gain medium mechanism. The stimulation and evolution discipline of the Stokes wave are analyzed in depth. The application of the Self Phase Modulation to suppress the Stimulated Brillouin Scatter in the high power amplifier is proposed for the first time, simulation results verify the simpleness and feasibility of this method.The doped photonic crystal fiber is introduced as the amplifier gain medium. Rod-type Photonic Crystal Fiber for 1.5μm band with 120μm core diameter, 300μm inner cladding diameter and 1.5mm out cladding diameter is designed in theory for the first time. This is the largest core diameter in the 1.5μm band. The mJ level pulse energy can be obtained in the ns level pulse amplification, meanwhile maintaining single mode output.Allow for the serious limitation caused by the Yb ions band ASE, the photonic crystal band gap fiber with the band gap located in the 1.5μm band is designed in theory for the first time. The optimum parameters are: silica rod diameter is 1μm, the distance between silica rods is 4μm, the refractive index difference between the background material and silica rod is 0.1. Theory analysis shows that the 1550nm light is well confined in the core by the band gap. The mode energy distribution exhibits the star profile, but most of the energy is still maintained in the core area. The 0.1nm bandwidth of the band gap is enough to filter the ASE. The photonic crystal band gap fiber suppresses the Stimulated Brillouin Scatter due to its own physical structure, which is viewed as the optimum solution to the ASE problem.The all fiber two stages amplifier experiment based on the Er/Yb co-doped double clad fiber and the Master Oscillator Power Amplifier technology is presented.: The maximal slope efficiency is 29%, maximal output power is 1.52W, and the degree of the power stability is 0.4% for 1550nm continuous wave amplification.The maximal slope efficiency is 22.56% for pulse amplification with 1 kHz repetition rate, which is the maximal slope efficiency at such low repetition rate in the 1.5μm band to our knowledge.And the maximal power is 1W, the degree of the power stability is 0.45%.The experimental data are very useful in the high power 1.5μm band amplifier design.
Keywords/Search Tags:High power Er/Yb co-doped fiber amplifier, Stimulated Brillouin Scatter, Photonic Crystal Fiber, Master Oscillator Power Amplifier, All fiber
PDF Full Text Request
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