Amrita Kumar Sana

Silicon photonic crystal resonators for label free biosensor

We report the fabrication and characterization of a two-dimensional (2D) silicon photonic crystal biosensor consisting of waveguides and cavity-type and defect-type resonators for enhancing the interactions between light and biomaterials. Sensitivity was measured using sucrose solution and the sensor showed the highest sensitivity [1570 nm/RIU (refractive index unit)] ever reported. We also investigated cavity size effects on resonance wavelength shift, and we observed that a large cavity exhibits a greater resonance wavelength shift. The fabricated sensor has shown a high Q of ~105 in water and a device figure of merit of 1.2 × 105, which represent the improvements of the device performance over other photonic-crystal-based sensors.

Detection of prostate specific antigen using silicon photonic crystal nanocavity resonator

In this work, we investigated photonic crystal (PhC) based double nanocavity resonator biosensor. The sensor performance has confirmed by both sucrose and prostate specific antigen (PSA, a protein biomarker associated with prostate cancer). The device sensitivity and quality factor in sucrose solution are 1571 nm/RIU (Refractive Index Unit) and 2×105 respectively. By using special antigen-antibody reaction, we successfully detected PSA concentration as low as 0.5 ng/mL.

Temperature dependence of resonance characteristics of silicon resonators and thermal stability improvement by differential operation method

In this paper, we describe the mechanism and solution for dominating temperature effects on refractive-index-based Si optical resonator sensors such as ring resonator and photonic crystal resonator sensors. The temperature change affects the silicon refractive index and also the resonator mechanical shape. As a result, it is reported that the refractive index change is marked, whereas the mechanical deformation effect is negligible. We also demonstrated that the differential operation is effective for suppressing the temperature effect for Si ring resonator sensors.