摘要
In this paper,a Bragg reflector is proposed by placing periodic metallic gratings in the center of a metal-insulator-metal(MIM)waveguide.According to the effective refractive index modulation caused by different waveguide widths in a period,a reflection channel with a large bandwidth is firstly achieved.Besides,the Mach-Zehnder interference(MZI)effect arises by shifting the gratings away from the waveguide center.Owing to different optical paths with unequal indices on both sides of the grating,a narrow MZI band gap will be obtained.It is interesting to find out that the Bragg reflector and Mach-Zehnder interferometer are immune to each other,and their wavelengths can be manipulated by the period and the grating length,respectively.Additionally,we can obtain three MZI channels and one Bragg reflection channel by integrating three different gratings into a large period.The performances are investigated by finite-difference time-domain(FDTD)simulations.In the index range of 1.33–1.36,the maximum sensitivity for the structure is as high as 1500 nm/RIU,and it is believed that this proposed structure can find widely applications in the chip-scale optical communication and sensing areas.
基金
supported by the National Key Research and Development Program of China(Grant No.2019YFB1803505)
the National Natural Science Foundation of China(Grant Nos.U2001601,62175039,and 61925501)
the Science and Technology Project of Guangzhou(Grant No.201904010243)
Major Special Projects in Guangdong Province(Grant No.2018B010114002)
the Engineering Research Center of Digital Imaging and Display,Ministry of Education,Soochow University(Grant No.SDGC2133)
the Program for Guangdong Introducing Innovative and Enterpreneurial Teams.
