Thermal cooling analysis and validation of the ytterbium doped double clad fiber laser by a general analytic method

Long optical fiber is usually coiled on the surface of the substrate. Spreading thermal resistance is an important factor affecting thermal properties of optical fiber in this encapsulation way. This paper adopts a concise general analytic method to calculate spreading thermal resistance of the eccentric heat source formed in the rectangular channel. The on-site testing of active doped double clad fiber(DDCF)laser is also carried out. It is observed that the output light efficiency is high after the fiber loses heat through the plate which conforms to the needs of normal fiber laser light output efficiency of 70%-80%. The analytic value is in line with the changing trend of the experimental value, with the error of the temperature measurement points within ±8.8%. The third segment rules out the influence of the optical fiber coupler location and the temperature of coupling point. When the pump power ranges from 4.4 W to 31.07 W, the error range between the experiment and analytics is within −4.14% to −0.82%. The layout plan of the fiber has a certain effect on the temperature uniformity of the fiber laser. It is demonstrated that the analytic method and mathematical assumption are reliable in the cooling design of the optical fiber.