Characteristics Study On Nd-doped Large-mode-area Double-clad Photonic Crystal Fiber Lasers

Neodymium ions(Nd³⁺)are the first trivalent rare earth ions used in lasers,which can be pumped with laser diodes?LDs?and have been stimulated in hundreds of different materials.Nd³⁺ doped lasers have significant applications in the fields of military,industrial,biological,medical,and scientific research fields,and so on.The research on Nd³⁺ doped fiber lasers has become one of the hot scientific topics in recent years because of its advantages such as compact structure,high stability,resistance to interference,high quality,etc.At present,the average output powers of single-mode Nd³⁺ doped fiber lasers are mostly at mW level.Although the conventional double-clad Nd³⁺ doped fiber lasers have high output powers,they belong to multimode operation,which leads to the decrease of beam quality.This defect can be eliminated in the photonic crystal fiber by reasonable structure design,which has the advantages of large mode area and no cutoff single-mode characteristics.In this paper,we studied the properties of CW laser and mode-locked pulse laser based on Nd³⁺ doped large-mode-area double-clad polarization-maintaining photonic crystal fiber at 1.06? m region.The contents of this paper were as follows:1.Based on the parameter of air holes size,periodic array,and so on,Nd³⁺ doped large-mode-area double-clad polarization-maintaining photonic crystal fiber were studied with spectral characteristics.Nd³⁺ doped photonic crystal fiber was analyzed with mode characteristics,dispersion characteristics,polarization characteristics,nonlinearity effects and loss characteristics,which was a reference and guidance in lasers.2.Nd³⁺ doped large-mode-area double-clad polarization-maintaining photonic crystal fiber pumped by LD was investigated in the continunous-wave laser.When the maximum output power was 5.95 W,the beam quality factor M2 was less than 1.30 and the polarization crosstalk was-7.9d B,which had the advantage of single-mode transmission characteristics and polarization characteristics to achieve high output power laser with high beam quality.3.Nd³⁺ doped large-mode-area double-clad polarization-maintaining photonic crystal fiber was studied in the all normal dispersion mode-locked laser.With semiconductor saturable absorption mirrors?SESAM?as modulator,it was used in the mode-locked laser at 1? m,without any dispersion compensating elements.When the pulse duration was 73.1ps,the maximum average output power and the single pulse energy were 236.8mW and 17.3nJ,respectively,which can reduce nonlinearity effects for the mode-locked pulse laser of high output power.4.Nd³⁺ doped large-mode-area double-clad polarization-maintaining photonic crystal fiber laser amplifier was designed with homemade Nd:YVO4 crystal continuous-wave laser as the seed to achieve the maximum output power of 8.75 W.In this paper,it was concluded that the high power continuous-wave laser,the mode-locked pulse laser and the laser amplifier of Nd³⁺ doped polarization-maintaining photonic crystal fibers,which was good reference and impetus value to further development of the research in this field.