Hung Yung-Jr, Kao Chia-Wei, Kao Tzu-Chieh, Huang Chia-Wei, Lin Jia-Jin, Yin Chuan-Ci
Opt Express. 2018 Oct 15;26(21):27515-27527. doi: 10.1364/OE.26.027515.
In this work we introduce a tunable GMR filter based on continuously period-chirped (ΔP = 130 nm) gratings using a TaO waveguide layer with graded thickness (ΔT = 36 nm). The structure of the gradient-period grating is defined using a modified Lloyd's mirror interferometer with a convex mirror, and TaO film used for the gradient is deposited using masked e-beam evaporation. The as-realized chirped GMR filter provides sharp transmission dips at resonant wavelengths with a filter bandwidth of approximately 4.2 nm and 0.78 nm when respectively applied to TE and TM polarized light under normal incidence. Gradually sweeping the chirped GMR filter makes it possible to monotonically sweep through resonant wavelengths from 500 to 700 nm, while maintaining stable filter bandwidth and transmission intensity. The optical spectrum of the incoming light can then be loyally reconstructed accordingly. We successfully demonstrate the spectrum reconstruction of a white light emitting diode and a dual-peak laser beam using the proposed chirped GMR filter as a dispersive device.
在这项工作中，我们介绍了一种基于连续周期啁啾（ΔP = 130 nm）光栅的可调谐巨磁电阻（GMR）滤波器，该光栅使用具有渐变厚度（ΔT = 36 nm）的TaO波导层。渐变周期光栅的结构是使用带有凸面镜的改进型劳埃德镜干涉仪定义的，用于渐变的TaO薄膜是通过掩膜电子束蒸发沉积的。所实现的啁啾GMR滤波器在共振波长处提供尖锐的传输凹陷，当在正入射下分别应用于TE和TM偏振光时，滤波器带宽分别约为4.2 nm和0.78 nm。逐渐扫描啁啾GMR滤波器使得能够从500到700 nm单调扫描共振波长，同时保持稳定的滤波器带宽和传输强度。然后可以相应地忠实地重建入射光的光谱。我们成功地使用所提出的啁啾GMR滤波器作为色散装置演示了白光发光二极管和双峰激光束的光谱重建。
