Miller Gary A, Peele John R, Askins Charles G, Cranch Geoffrey A
Optical Sciences Division, Naval Research Laboratory, Washington, DC 20375, USA.
Appl Opt. 2011 Dec 20;50(36):6617-26. doi: 10.1364/AO.50.006617.
Coupling coefficients of various grating types and strengths are calculated from measurements of the complex reflectivity using an applied thermal chirp and optical frequency domain reflectometry (OFDR). The complex reflectivity is then utilized by a layer peeling algorithm to determine the coupling coefficient of the thermally chirped grating. A guess of the temperature profile enables the coupling coefficient of the unchirped grating to be estimated. An iterative algorithm is then used to converge on the exact coupling coefficient, employing an error minimization method applied to the reflectivity spectra. This technique removes the need for a reference grating while preserving the spatial resolution obtained with the initial OFDR measurement. Successful reconstruction of gratings with integrated |κ|L ~ 9.0 are demonstrated with a spatial resolution of less than 100 μm.
利用施加的热啁啾和光频域反射仪（OFDR）通过对复反射率的测量来计算各种光栅类型和强度的耦合系数。然后，复反射率被层剥离算法用于确定热啁啾光栅的耦合系数。温度分布的猜测使得能够估计未啁啾光栅的耦合系数。接着使用迭代算法，采用应用于反射率光谱的误差最小化方法，收敛到精确的耦合系数。该技术无需参考光栅，同时保留了初始OFDR测量所获得的空间分辨率。展示了以小于100μm的空间分辨率成功重建积分|κ|L~9.0的光栅。
