Title: Characterization of Gradient Index Fibers Show Chinese title

Title: 梯度折射率光纤的表征

Abstract: Gradient index (GRIN) fibers are used to improve the design of many fiber optic devices. However, the properties of the GRIN fiber must be determined to optimally engineer a device which incorporates GRIN fiber components. The index of refraction of most GRIN fibers varies quadratically in the radial direction, where the quadratic coefficient is characterized by the gradient index constant $g$. We measured $g$ for Thorlabs GIF50C GRIN fiber at both $780~\mathrm{nm}$ and $1550~\mathrm{nm}$ using equipment which is commonly available in an optics laboratory. This measurement was achieve by profiling the beam exiting various lengths of GRIN fiber. A custom-built beam profiler was used, which enabled the beam position to be referenced with respect to the facet of the GRIN fiber. We report a gradient index constant of $0.0057~\mathrm{\mu m}^{-1} \pm 0.0001~\mathrm{\mu m}^{-1}$ at $780~\mathrm{nm}$ and $0.0055~\mathrm{\mu m}^{-1} \pm 0.0001~\mathrm{\mu m}^{-1}$ at $1550~\mathrm{nm}$. These results are in close agreement with previously reported gradient index constant measurements made for different wavelengths. Show Chinese abstract

Abstract: 梯度折射率（GRIN）光纤用于改进许多光纤器件的设计。 然而，必须确定GRIN光纤的特性，以最佳地设计包含GRIN光纤组件的器件。 大多数GRIN光纤的折射率在径向方向上呈二次变化，其中二次系数由梯度折射率常数$g$表征。 我们使用光学实验室中常见的设备，在$780~\mathrm{nm}$和$1550~\mathrm{nm}$波长下测量了Thorlabs GIF50C GRIN光纤的$g$。 该测量是通过对不同长度的GRIN光纤出射光束进行剖面分析实现的。 使用了一种自制的光束剖面仪，该仪器使光束位置能够相对于GRIN光纤的端面进行参考。 我们报告在$0.0057~\mathrm{\mu m}^{-1} \pm 0.0001~\mathrm{\mu m}^{-1}$时的梯度折射率常数为$780~\mathrm{nm}$，在$0.0055~\mathrm{\mu m}^{-1} \pm 0.0001~\mathrm{\mu m}^{-1}$时为$1550~\mathrm{nm}$。 这些结果与之前针对不同波长报告的梯度折射率常数测量结果高度一致。