关键词: 表面等离极化激元/
折射率传感器/
金属-介质-金属波导/
光学谐振腔
English Abstract
Refractive index sensor and filter of metal-insulator-metal waveguide based on ring resonator embedded by cross structure
Qi Yun-Ping1,Zhang Xue-Wei1,
Zhou Pei-Yang1,
Hu Bing-Bing1,
Wang Xiang-Xian2
1.Engineering Research Center of Gansu Province for Intelligent Information Technology and Application, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070, China;
2.School of Science, Lanzhou University of Technology, Lanzhou 730050, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 61367005), the Natural Science Foundation of Gansu Province, China (Grant No. 17JR5RA078), Northwest Normal University Young Teachers' Scientific Research Capability Upgrading Program (Grant No. NWNU-LKQN-17-6), and the Northwest Normal University Graduate Student Innovation Ability Enhancement Program Foundation, China (Grant No. CX2018Y167).Received Date:20 April 2018
Accepted Date:19 July 2018
Published Online:05 October 2018
Abstract:Continuous improvement in nanofabrication and nano-characterization capabilities have changed projections about the role that metals could play in developing the new optical devices. Surface plasmon polaritons are evanescent waves that propagate along a metal-dielectric interface. They can be laterally confined below the diffraction limit by using subwavelength metal structures, rendering them attractive to the development of miniaturized optical devices. A surface plasmon polariton refractive index sensor and filter which consist of two metal-insulator-metal (MIM) waveguides coupled to each other by a ring resonator embedded by cross structure are proposed. And the transmission characteristics of surface plasmon polaritons are studied in our proposed structure. The transmission properties of such a structure are simulated by the finite element method, and the eigenvalue wavelengths of the ring resonator are calculated theoretically. The sensing characteristics of such a structure are systematically analyzed by investigating the transmission spectrum. The results show that there are three resonance peaks in the transmission spectrum, that is, three resonance modes corresponding to the eigenvalue solutions of the first, second and third-order Bessel eigen-function equations, and each of which has a linear relationship with the refractive index of the material under sensing. Through the optimization of structural parameters, we achieve a theoretical value of the refractive index sensitivity (S) as high as 1500 nm/RIU, and the corresponding sensing resolution is 1.3310-4 RIU. More importantly, it is sensitive to none of the parameters of our proposed structure, which means that the sensitivity of the sensor is immune to the fabrication deviation. In addition, by the resonant theory of ring resonator, we find a linear relationship between the resonance wavelength and the radius of ring resonator. So the resonance wavelength can be easily manipulated by adjusting the radius and refractive index. In addition, the positions of transmission peaks can be easily modulated by changing the radius of the ring, which can be used to design band-pass filter for a large wavelength range. Moreover, the transmission intensity and the transmission bandwidth decrease as spacing distance between the MIM waveguide and ring cavity increases. These results would be helpful in designing the refractive index sensor of high-sensitivity and band-pass filters, and have guiding significance for biological sensor applications.
Keywords: surface plasmon polaritons/
refractive index sensors/
metal-insulator-metal waveguides/
optical resonators
