热激法光子晶体光纤光栅制备工艺中热传导特性研究

Heat transfer characteristics in fabrication of heat method in photonic crystal fiber grating

研究了基于结构性改变的光子晶体光纤光栅的热激法制备工艺,理论分析了此种工艺的成栅原理,采用热传导理论和有限元法研究了制备过程中光子晶体光纤中的温度场分布,以及包层空气孔结构和激光参数对成栅效果的影响.研究结果表明,利用光子晶体光纤包层空气孔周期性塌缩可以形成光栅;采用两点热激法时,能够实现能量在光纤径向均匀分布,轴向近似于高斯分布;包层气孔结构加速了成栅过程,相同光斑尺寸下,光纤塌缩所需激光功率随气孔层数和气孔半径的增大而减小;最后,对包层空气孔结构为1层到7层的光子晶体光纤热激过程进行仿真,得到了空气填充率与所需激光功率的关系.此种光纤光栅从根本上克服了传统光栅热稳定性和长期稳定性不佳的问题,在光纤传感等领域具有较大的潜在应用价值.

The grating fabrication technology with heat method in photonic crystal fiber based on its structural change is researched. The principle of photonic crystal fiber grating is analyzed theor etically. Heat transfer theory and finite element method are both used to analyze the thermal field distribution in the fiber,as well as the influence of air hole structure in the cladding,and the parameters of laser beam in the process of grating fabrication are discussed. The research results show that the grating can be formed by the periodic air hole collapse in the cladding of photonic crystal fiber. Under double-point heating,the energy will be uniformly distributed in the radial direction and approximated by the Gaussian distribution in the axial direction. The collapsed air holes in the cladding accelerate the process of forming grating. In the same size of luminous spot,as the layers and the radii of air holes increase,the laser power for collapsing fiber decreases. Moreover,the relationship between laser power and air filling rate is obtained by stimulating the grating fabrication process in photonic crystal fiber with 1 to 7 layers of air holes. This kind of photonic crystal fiber grating can improve the thermal and long-term stability of conventional grating,and so it will have great potential applications in the relevant fields of optical fiber sensors.