As the normalized modal areas is ultrasmall for different H t values, we obtain the maximum propagation length of 2.49 × 103 μm for H t = 320 nm. The propagation length of the AHP waveguide increases 122% than that of the SHP waveguide on a substrate. Compared to the ideal condition of the SHP in air

cladding, the propagation length of the AHP waveguide is approximately equal to that of the SHP waveguide in air (2.38 × 103 μm) with a comparable normalized modal area. Thus, the introduced asymmetry to the structure of the SHP waveguide is vital to the extension of the propagation length while exerting little effect on the normalized modal area. The phenomenon in Figure 4b is similar to that in Figure 4a, but the performance of the silica-based AHP waveguide is better than that of the MgF2-based AHP waveguide. Figure 4 Propagation length and normalized modal area of silica- Bafilomycin A1 cost and MgF 2 -based AHP waveguide versus height of mismatch. (a) Silica- and (b) MgF2-based AHP waveguide. The insets indicate electromagnetic energy density profiles of different

Microtubule Associated inhibitor heights of mismatch. Conclusions In conclusion, we reveal that the AHP waveguide combining the advantages of symmetric (long-range) SP mode and hybrid plasmonic waveguides is capable of supporting long-range propagation of the guided waves with nanoscale mode confinement. The proposed structure is realized by introducing an asymmetry into the SHP waveguide. Theoretical calculations show that the AHP waveguide can eliminate the effect of a silica substrate on the guiding properties of the SHP waveguide and restores the symmetry of SP mode. Thus, the AHP waveguide on a substrate can perform the same as the SHP waveguide embedded in air cladding. Considering different materials of the low index gaps in the AHP waveguide, the performance of the silica-based AHP waveguide is better than the MgF2-based AHP waveguide. The proposed AHP waveguide can be conveniently fabricated by existing buy JNJ-26481585 technologies like layered deposition or thermal oxidation. This may have practical applications

in highly integrated circuits as plasmonic interconnects. Acknowledgements This work was supported by the National Basic Research Program of China (2010CB327605), National Natural Alanine-glyoxylate transaminase Science Foundation of China (61077049), Program for New Century Excellent Talents in University of China (NCET-08-0736), 111 Project of China and BUPT Excellent Ph. D. Students Foundation (CX201322). References 1. Polman A: Applied physics plasmonics applied. Science 2008, 322:868–869.CrossRef 2. Gramotnev DK, Bozhevlnyi SI: Plasmonic beyond the diffraction limit. Nature Photon 2010, 4:83–91.CrossRef 3. William LB, Alain D, Thomas WE: Surface plasmon subwavelength optics. Nature 2003, 424:824–830.CrossRef 4. Ozbay E: Plasmonics: merging photonics and electronics at nanoscale dimensions. Science 2006, 311:189–193.