UNAM, Institute of Materials Science and Nanotechnology, Bilkent University, Ankara, 06800, Turkey.
Lab Chip. 2011 Jan 21;11(2):282-7. doi: 10.1039/c0lc00081g. Epub 2010 Oct 29.
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 × 10(-6) RIU/√Hz is obtained by using an 8 mW He-Ne laser, compared to a shot-noise limited theoretical sensitivity of 5.61 × 10(-9) RIU/√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.
在这项工作中，我们展示了一种集成传感器，它将光栅耦合等离子体共振表面与平面光电二极管结合在一起。等离子体增强传输被用作敏感折射率 (RI) 传感机制。通过在准直光束的入射角接近尖锐等离子体共振条件的情况下进行调谐，监测光的增强传输，从而通过集成光电二极管进行监测。有效折射率 (RI) 的微小变化会改变共振角，从而导致光电流发生变化。由于平面传感机制，该设计允许高的感测点密度。在设计中，不存在孔，这有利于光的谐振传输，允许易于实现的制造过程和对制造误差的相对不敏感性。理论和实验结果吻合良好。与理论灵敏度的 5.61×10(-9) RIU/√Hz 相比，使用 8 mW 氦氖激光获得了等效的长期 RI 噪声为 6.3×10(-6) RIU/√Hz。该器件具有光栅耦合等离子体共振的全部优势，例如对非零方位角入射角的灵敏度增强。讨论了使用平衡检测和最佳等离子体耦合条件的进一步灵敏度增强。
