基于电光材料亚波长金属复合结构的高分辨率芯片光谱仪机理及实验研究

Restricted by the optical diffracted limit, the dimension of the traditional spectrometer with high resolution is hard to reach the nanoscale. In this project, the electro-optical material is introduced into the subwavelength metal structure to form the nanoscaled spectrum separation mechanism. Use the high resolution voltage to modulate the refractive index of the electro-optical material, then modulate the transmission spectrum of the metal subwavelength structure to realize the high resolution spectrum separation. By researching the electromagnetic mode and the transmission property of the surface plasmon in the subwavelength structure under the index modulation of the electro-optical material, and analyzing the relationship between the modulation voltage and the wavelength, bandwith, transmission and quality factor of the transmission spectrum, build the physical spectrum separation model of the confused subwavelength structure and establish the design method of that the structure to realize the chip spectrometer with high resolution. Investigate the fabrication property of the subwavelength structure confused with the electro-optical material and metal, and establish the fabrication process of the on-chip spectrometer formed by the structure. Based on these works, carry out the spectrum testing experiments. By processing the measured data, obtain the experiment resolution of the on-chip spectrometer and validate the correctness of the spectrum separation theory with the electro-optical material confused subwavelength structure. The proposed technic is a new mechanism to realize the spectrum separation. The acting part is a thin film with nanoscaled subwavelength structure, which is integrated with the circuit of the modulation voltage and the optical intensity detector to form the on-chip spectrometer. It has the advantages of the high resolution, light weight and small size etc. that the spectrometer will have a mass application in the universe detections and biological analyses etc.

受衍射极限限制，传统光谱仪在保持高分辨率的同时，难以进一步向纳米尺度小型化。本项目提出利用折射率可调的电光材料形成纳米尺度的亚波长金属复合分光结构，通过电压高精度调制电光材料折射率方式改变亚波长结构异常透射谱位置，实现高分光率的光谱分光。通过研究电光材料折射率调制下亚波长金属复合结构的表面等离子体电磁模式与传输特性，分析调制电压对其透射谱位置、带宽、透过率及品质因素的调制规律，建立电光材料亚波长金属复合结构的分光物理模型及其实现高分辨率芯片光谱仪的设计方法。研究电光材料亚波长金属复合结构的加工工艺及其形成芯片光谱仪的制备方法，并在此基础上开展光谱测试实验，获得实验验证。该技术为一种新型的分光机制，分光结构为一层纳米尺度的亚波长金属结构膜，与调制电压电路及光电探测器集成即形成芯片光谱仪，具有高分辨率、轻量、便携等特点，在航空航天探测、生物分析等领域将具有广泛的应用前景。

受衍射极限限制，传统光谱仪在保持高分辨率的同时，难以进一步向纳米尺度小型化。本项目提出利用折射率可调的电光材料形成纳米尺度的亚波长金属复合分光结构，通过电压高精度调制电光材料折射率方式改变亚波长结构异常透射谱位置，实现高分光率的光谱分光。项目开展的主要研究内容与成果包括：（1）研究了金属亚波长结构/电光材料复合结构的分光原理，建立了相应的光谱探测理论模型。具体包括基于Maxwell电磁理论和波动光学传输理论，借鉴时域有限差分法数值计算方法，研究了金属亚波长结构滤波特性的调制规律，在此基础上提出了基于稀疏恢复算法的光谱探测技术，并经理论推导建立了光谱探测物理模型，为器件的实现奠定了重要理论基础；（2）研究了以向列相双折射液晶为电光材料和金属亚波长滤波结构复合的芯片光谱仪分光器件的制备方法，通过EBL纳米结构加工工艺，完成了金属亚波长滤波结构的准确制备，结合液晶器件的制备工艺，实现了液晶/亚波长金属结构复合的芯片型光谱仪原型器件制备，器件分光区域面积仅0.42×0.31mm；（3）开展了所提出和制备的光谱仪分光器件的光谱探测实验，实现了器件的功能验证。具体包括探测了波长为650nm的单频光，获得器件的光谱分辨率达到0.3nm，探测了窄带滤波器、罗丹明化学试剂以及ITO玻璃透射光谱等，系列实验表明该光谱仪探测光谱形状准确、误差小，验证了理论的正确性。该器件由于分光区域面积小，光谱分辨率高，又可形成高集成度的阵列型高光谱成像器件，因此在便携式移动终端、航空航天领域具有广泛应用前景。