掺铥镧铝硅酸盐玻璃光子晶体光纤制备及光学特性

Preparation and optical properties of thulium doped lanthanum aluminum silicate glass photonic crystal fiber

镧铝硅酸盐玻璃具有稀土离子溶解度高、热稳定性好等优异的光学性能和优良的物理化学性质,其部分物理化学性质与石英相近,易与石英玻璃结合进行特种光纤制备,被认为是一种理想的激光玻璃基质材料.本文采用传统高温熔融法成功研制出一系列不同浓度Tm^(3+)掺杂镧铝硅酸盐玻璃,以掺铥镧铝硅酸盐玻璃为纤芯,采用管棒堆叠法制备出掺铥双包层光子晶体光纤.实验研究了掺铥镧铝硅酸盐玻璃及其光纤的吸收、荧光、激光等光学特性,研究结果表明,掺铥镧铝硅酸盐玻璃及其光子晶体光纤适于2μm波段激光输出,为2μm波段高功率光纤激光器的研究提供了一种新的途径.

Lanthanum aluminum silicate glass has excellent optical properties,such as high solubility of rare earth ions,good thermal stability,and excellent physicochemical properties.Some of its physicochemical properties are similar to those of silica glass,so it is easy to combine with silica glass to fabricate special optical fibers.It is considered to be an ideal laser glass matrix material.In this paper,a series of Tm3+doped lanthanum aluminum silicate glasses with different concentrations for xTm_(2)O_(3)-(70−x)SiO_(2)-21Al_(2)O_(3)-9La_(2)O_(3)(x=0.2%,0.4%,0.6%,0.8%,1%,mole fraction)are successfully developed by the traditional high-temperature melting method.Using thulium-doped lanthanum aluminum silicate glass as the fiber core,thulium-doped doublecladding photonic crystal optical fibers are prepared by the stack-and-draw technique and rod in tube method.The core diameter of the thulium-doped lanthanum aluminosilicate glass double-clad photonic crystal fiber is as long as 21.7μm,the inner cladding diameter is about 119.3μm,and the outer diameter is about 236.8μm.The optical properties of thulium-doped lanthanum aluminum silicate glass and its optical fiber are studied experimentally.Under the excitation of a 793 nm laser,the fluorescence bandwidth of thulium-doped lanthanum aluminum silicate glass reaches 223 nm in a wavelength range of 1550−2050 nm.The fiber laser constructed with thulium-doped lanthanum alumino-silicate glass fiber achieves a laser operating at around 2μm.The fiber laser resonant cavity consists of a pair of dichroic mirrors.The front dichroic mirror has high transmittance for light at 793 nm and high reflectivity(99.9%)for the light within a wavelength range of 1850−2050 nm.The back dichroic mirror has high reflectivity(99.9%)for light at 793 nm and high transmittance(~15%)at 2050 nm.Under the experimental conditions in our laboratory,the laser power reaches 253 mW.The highest slope efficiency is 9.67%,which is close to that of the thulium-doped glass fiber laser reported in the literature.It is also found that the central wavelength of fiber laser is shifted toward the longer wavelength with the increase of the optical fiber's length.These results suggest that thulium-doped lanthanum aluminum silicate glass and thulium-doped photonic crystal fiber are suitable for 2-μm fiber laser.