Research On High Power Er³⁺ /Yb³⁺-Codoped All Fiber Laser

The emergence of cladding-pumped technology brings the revolution of high-power fiber laser, and the adhibition of Er³⁺/Yb³⁺-codoped fiber laser expands the pumping source's range and avoids the concentration quenching of Er³⁺-doped fiber laser.Because of the nice beam quality and high power density,high power Er³⁺/Yb³⁺-codoped fiber laser can be used for long-distance communication ,still as pump source of Er³⁺ and Tm³⁺ doped crystal, obtain high pump efficiency,so it gets more and more attention.In theory, base on the rate equations of Er³⁺/Yb³⁺-codoped fiber laser, the power transmission equations are obtained in the steady state case,compained with the actuality ,the boundary and power output function are acquired.From the rate equation and power propagation, the optimum fiber length is confirmed through numerical simulation ,and the influence of cavity mirrors reflectivity,doping density,pump power and background loss to output power and optimum fiber length are analysed.Experimentally,under the premise of laser diode's safety, in terms of the output power and redshift of LD ,the optimum working condition is determined. Cladding-pumped Er³⁺/Yb³⁺ -codoped fiber laser with many rush oscillation at 1.5μm has been practiced, and the slope efficiency of fiber laser reaches 18.3%. The single cladding grating is dealed successfully as double cladding grating for the first time,play the role of input mirror and the fiber end face is used for output mirror,the all fiber lasers who select the wavelength by fiber grating are realized: one has the centre wavelength of 1569.7nm with the linewidth of 36.0pm,the maximum output of 6.3W and the slope efficiency of 22.9%;After changing the grating and optimizing the fiber length,the other one who has the centre wavelength of 1531.9nm with the linewidth of 34.9pm,the maximum output of 4.02W and the slope efficiency of 21.3% is realized.The factors who influences the beam quality are analysed.By the way of fusing the signal cladding fiber to the rare earth-doped fiber,the pump power,laser power and fluorescent who transfer in the cladding could be peeling.The beam quality M² is improved from 17.2 to 1.82 by fusing the matching fiber to the Er³⁺/Yb³⁺-codoped fiber.