Subwavelength filter and sensor design based on end-coupled composited ring-groove resonator

A plasmonic filter and sensor is designed based on an end-coupled ring-groove composited resonator(RGCR).According to the magnetic field distributions of the resonance modes,a horizontal or vertical groove is added to the perfect ring resonator,and the transmission peaks for the 1st and the 2nd modes can be linearly changed by the length of the groove.In this case,the proposed structure can act as an on-chip optical filter with flexible wavelength manipulation.When the groove is rotated with an angle of?/4,Fano resonance arises due to the mode interference.Dual asymmetric sharp transmission peaks are achieved around the wavelength of the former 2nd resonance mode.High figure of merit and high sensitivity are obtained for the structure,and it is believed that the device can find widely applications in the biochemistry sensing area.The corresponding spectra and the propagation characteristics are numerically investigated by using the finite-difference time-domain method.

An Integrated-Plasmonic Chip of Bragg Reflection and Mach-Zehnder Interference Based on Metal-Insulator-Metal Waveguide

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.

A Plasmonic Refractive-Index Sensor Based Multiple Fano Resonance Multiplexing in Slot-Cavity Resonant System

In this paper,a sub-wavelength metal-insulator-metal(MIM)waveguide structure is proposed by using a cross-shape rectangular cavity,of which wings are coupled with two rectangular cavities.Firstly,a cross-shape rectangular cavity is placed between the input and output MIM waveguides.According to the mutual interference between bright and dark modes,three Fano resonant peaks are generated.Secondly,by adding a rectangular cavity on the left wing of the cross shaped one,five asymmetric Fano resonance peaks are obtained.Thirdly,six asymmetric Fano resonance peaks are achieved after adding another cavity on the right wing.Finally,the finite-difference-time-domain(FDTD)method and multimode interference coupled-mode theory(MICMT)are used to simulate and analyze the coupled plasmonic resonant system,respectively.The highest sensitivity of 1 OOOnm/RIU is achieved.