Semi-circle long-range dielectric-loaded surface plasmon-polariton waveguide (LR-DLSPPW) is proposed, in which a thin and narrow metal stripe (15-nm-thick and 500-nm-wide) is sandwiched between a semi-circle dielectric ridge(with the refractive index of 1.535 ,the radius of 777 nm) and a dielectric film (with the refractive index of 1.493) supported by low-index substrate (with the refractive index of 1.34). The mode effective index, propagation length, mode width and figures of merit of the fundamental mode supported using the finite-element method are calculated at the telecom wavelength λ =1.55μm for different dimensions (t) of the dielectric film. It was calculated that the optimized structure have the maximized parameters with figures of merit 3.75×10¬6and propagation length 3.7mm at t=570 nm. The semi-circle LR-DLSPPW structure is found to exhibit about 20% increase of the propagation length as compared to the conventional rectangular LR-DLSPPW while ridge thickness t≤600 nm. The proposed configuration allows for easy connection to electrodes enabling, and is technologically simple being compatible with planar fabrication using UV-lithography.
Straight Long-Range Surface Plasmon Polariton Waveguide Sensor Operating at λ0 = 850 nm
