Characteristic analysis of gain guided index antiguided large-mode-area fiber lasers

In order to study the power distribution and output characteristics of gain guided index antiguided (GG-IAG) fiber lasers, rate equations of basic model light of double-clad GG-IAG fiber lasers with end-pumping were established, based on the principle and structure characteristics of GG-IAG fibers. After solving the rate equations with tangential method and Runge-Kutta method, power distribution and output characteristics of basic model light were gained. The results show that parameters of fiber and laser cavity, such as fiber length, output lens reflectivity, have significant influence on gain distribution and output power of basic model light. When using a GG-IAG fiber with a radius of 100m, index step -0.00094 and concentration of ions 51026/m3 to construct a GG-IAG fiber laser, fiber length needs to be 3cm and output lens reflectivity is 0.98 and 0.3 respectively, in order to restrain LP11 model, and while inputing a 30W pump-light, 2.42W single-mode laser with large-mode-area can be obtained. The analysis shows that by optimally designing cavity mirror reflectivity and fiber length, fundamental mode output with certain efficiency can be obtained in a short length large-mode-area highly doped GG-IAG fiber.