Performance Characteristics of Single Frequency Er3+:Yb3+ Codoped Fiber Lasers

For much of this decade, interest has been sustained in developing high performance single frequency Er3+-fiber lasers1-3. For robust single frequency operation, these lasers need to be only centimeters long. Early grating-based fiber lasers relied on Er-germanosilicate fibers, but lasing powers were low - μW typically1,2, due to low pump absorption in the short cavity. Increasing the Er-concentration to increase absorption is however difficult. Germanosilicate fibers are prone to ion clustering, which degrades the efficiency and destablises4,5 the laser. Thus the need to amplify the laser power to useful levels of a mW or more is a drawback where low noise sources are desired.