Grating coupler integrated photodiodes for plasmon resonance based sensing
Ekiz, Okan O.
Guler, M. O.
Lab on a Chip
The Royal Society of Chemistry
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.
Please cite this item using this persistent URLhttp://hdl.handle.net/11693/13340
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.