An ultrahigh-contrast and broadband on-chip refractive index sensor based on a surface-plasmon-polariton interferometer.
Using a double-slit structure fabricated on a gold film or a subwavelength (300 nm) plasmonic waveguide, high-contrast and broadband plasmonic sensors based on the interference of surface plasmon polaritons (SPPs) are experimentally demonstrated on chips. By adjusting the focused spot position of the p-polarized incident light on the double-slit structure to compensate for the propagation loss of the SPPs, the interfering SPPs from the two slits have nearly equal intensities. As a result, nearly completely destructive interference can be experimentally achieved in a broad bandwidth (>200 nm), revealing the robust design and fabrication of the double-slit structure. More importantly, a high sensing figure of merit (FOM*) of >1 × 10(4) RIU(-1) (refractive index unit), which is much greater than the previous experimental results, is obtained at the destructive wavelength because of a high contrast ratio (C = 0.96). The high-contrast and broadband on-chip sensor fabricated on the subwavelength plasmonic waveguide may find important applications in the real-time sensing of particles and molecules.
State Key Laboratory for Mesoscopic Physics and Department of Physics, Peking University, Beijing 100871, China. jjchern@pku.edu.cn.
Yujia
Y
Wang
Jianjun
J
Chen
Chengwei
C
Sun
Kexiu
K
Rong
Hongyun
H
Li
Qihuang
Q
Gong
D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D003287:Contrast Media; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D007368:Interferometry / Q000295:instrumentation* / Q000379:methods; D008027:Light; D008853:Microscopy; D036103:Nanotechnology / Q000379:methods*; D009991:Oscillometry; D012031:Refractometry; D020349:Surface Plasmon Resonance / Q000295:instrumentation* / Q000379:methods
D003287:Contrast Media; D006046:Gold