Electrically tunable infrared filter based on the liquid crystal Fabry-Perot structure for spectral imaging detection.
Electrically tunable infrared filter based on the liquid crystal Fabry-Perot structure for spectral imaging detection.
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DOI：
10.1364/ao.53.005632
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发表时间：
2014-09
期刊：
影响因子：
1.9
通讯作者：
Huaidong Zhang;Afzal Muhammmad;Jun Luo;Q. Tong;Yu Lei;Xinyu Zhang;Hongshi Sang;C. Xie
中科院分区：
文献类型：
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作者：
Huaidong Zhang;Afzal Muhammmad;Jun Luo;Q. Tong;Yu Lei;Xinyu Zhang;Hongshi Sang;C. Xie
设计并制作了一种基于液晶（LC）法布里-珀罗（FP）键结构的电调谐红外（IR）滤波器，工作波长范围为5.5 ~ 12 μm。这两个平面反射镜具有非常高的反射率为95%，这是通过在双面抛光硒化锌晶片的一侧上沉积一层铝（Al）膜来成形的，被耦合到双镜FP腔中。LC材料填充到FP腔中，厚度为1.75 μm，用于构建LC-FP滤波器，这是一种典型的三明治结构。FP腔的顶镜和底镜还在Al膜上涂覆了厚度为100 nm的取向层。强烈摩擦所形成的配向层以形成相对深的V形槽，从而有效地锚LC分子。普通的光学测试显示出一些特殊的性质;例如在所测量的波长范围内存在三个透射峰，最小半峰全宽为120 nm，通过施加均方根（RMS）的电压驱动信号，成像波长的最大调节范围为500 nm，根据我们的模型设置，实验结果与模拟结果一致。通过不同均方根值的电压信号驱动LC-FP器件，获得了长波红外波段的光谱图像，展示了实现智能光谱成像以及进一步将LC-FP滤波器与红外焦平面阵列集成的前景。所研制的LC-FP滤波器具有成像波长电可调、结构和光电响应稳定性高、体积小、功耗低、填充因子高达95%以上等优点。
An electrically tunable infrared (IR) filter based on the liquid crystal (LC) Fabry-Perot (FP) key structure, which works in the wavelength range from 5.5 to 12 μm, is designed and fabricated successfully. Both planar reflective mirrors with a very high reflectivity of ∼95%, which are shaped by depositing a layer of aluminum (Al) film over one side of a double-sided polished zinc selenide wafer, are coupled into a dual-mirror FP cavity. The LC materials are filled into the FP cavity with a thickness of ∼7.5 μm for constructing the LC-FP filter, which is a typical type of sandwich architecture. The top and bottom mirrors of the FP cavity are further coated by an alignment layer with a thickness of ∼100 nm over Al film. The formed alignment layer is rubbed strongly to shape relatively deep V-grooves to anchor LC molecules effectively. Common optical tests show some particular properties; for instance, the existing three transmission peaks in the measured wavelength range, the minimum full width at half-maximum being ∼120 nm, and the maximum adjustment extent of the imaging wavelength being ∼500 nm through applying the voltage driving signal with a root mean square (RMS) value ranging from 0 to ∼19.8 V. The experiment results are consistent with the simulation, according to our model setup. The spectral images obtained in the long-wavelength IR range, through the LC-FP device driven by the voltage signal with a different RMS value, demonstrates the prospect of the realization of smart spectral imaging and further integrating the LC-FP filter with IR focal plane arrays. The developed LC-FP filters show some advantages, such as electrically tunable imaging wavelength, very high structural and photoelectronic response stability, small size and low power consumption, and a very high filling factor of more than 95% compared with common MEMS-FP spectral imaging approaches.