Grating coupler integrated photodiodes for plasmon resonance based sensing
Ekiz, Okan O.
Guler, M. O.
Please cite this item using this persistent URLhttp://hdl.handle.net/11693/13340
Lab on a Chip
The Royal Society of Chemistry
In this work, we demonstrate an integrated sensor combining a grating-coupled plasmon resonance surface with a planar photodiode. Plasmon enhanced transmission is employed as a sensitive refractive index (RI) sensing mechanism. Enhanced transmission of light is monitored via the integrated photodiode by tuning the angle of incidence of a collimated beam near the sharp plasmon resonance condition. Slight changes of the effective refractive index (RI) shift the resonance angle, resulting in a change in the photocurrent. Owing to the planar sensing mechanism, the design permits a high areal density of sensing spots. In the design, absence of holes that facilitate resonant transmission of light, allows an easy-to-implement fabrication procedure and relative insensitivity to fabrication errors. Theoretical and experimental results agree well. An equivalent long-term RI noise of 6.3 x 10(-6) RIU/root Hz is obtained by using an 8 mW He-Ne laser, compared to a shot-noise limited theoretical sensitivity of 5.61 x 10(-9) RIU/root Hz. The device features full benefits of grating-coupled plasmon resonance, such as enhancement of sensitivity for non-zero azimuthal angle of incidence. Further sensitivity enhancement using balanced detection and optimal plasmon coupling conditions are discussed.
Turker, B., Guner, H., Ayas, S., Ekiz, O. O., Acar, H., Guler, M. O., & Dâna, A. (2011). Grating coupler integrated photodiodes for plasmon resonance based sensing. Lab on a Chip, 11(2), 282-287.