Research progress in single-crystal fiber amplifiers

Owing to the special structure between fiber and crystal, single-crystal fiber has the merits of both fiber and crystal medium. For its advantages of high gain, simple thermal management, and small nonlinear effect, single-crystal fiber is widely used in ultrashort pulse amplification. The experimental research progress in singlecrystal fiber amplifiers is reviewed. Firstly, two kinds of single-crystal fiber preparation methods including micropulling down technique and laser heated pedestal growth technique arc introduced. Then along the principal clue of various means to improve the amplification performance of single-crystal fiber amplifiers, we summarize the research progress in Nd: YAG and Yb: YAG doped single-crystal fiber amplifiers and some new amplifiers with special structures in ultrashort pulse amplification. Finally, the applications and future development trends of singlecrystal fiber amplifiers arc prospected.