A one dimensional slot mode photonic crystal nanobeam cavity design for optical bio-sensing applications

Erdil, Mertcan
In this thesis, we presented a refractive index based optical bio-sensor, utilizing a slot mode one dimensional photonic crystal cavity as a transducing element. We benefited from the suitability of slotted one dimensional photonic crystal cavities for optical bio-sensing applications, owing to their capability of confining the light strongly in the low dielectric media. We described the theory behind the design, and also provided numerical analyses, characterizing the device performance. We also demonstrated a performance enhancement method, relying on an optomechanical feedback loop, which can enhance both the quality factor and the sensitivity of the resonant cavity. The enhancement mechanism is triggered when the target analyte enters the background medium and modifies the cavity slot width, by benefiting from the optical transverse gradient forces inside the cavity. By the help of the optomechanical feedback loop, the intrinsic trade-off between the performance factors can be eliminated, resulting in an improved figure of merit. In the thesis, we demonstrated the operation principle of the enhancement method, together with the numerical calculations necessary for the investigation of the level of enhancement. Our optomechanical feedback loop can be appended to any resonant structure vi without any modification, proposing a strong potential for our enhancement method to be utilized in other refractive index based optical bio-sensing schemes.
Citation Formats
M. Erdil, “A one dimensional slot mode photonic crystal nanobeam cavity design for optical bio-sensing applications,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Electrical and Electronics Engineering., Middle East Technical University, 2020.