Optical waveguide biosensors based on silicon-on-insulator (SOI) have been extensively investigated owing to its various advantages and many potential applications. In this article, we demonstrate a novel highly sensitive biosensor based on cascaded Mach-Zehnder interferometer (MZI) and ring resonator with the Vernier effect using wavelength interrogation. The experimental results show that the sensitivity reached 1,960 nm/RIU and 19,100 nm/RIU for sensors based on MZI alone and cascaded MZI-ring with Vernier effect, respectively. A biosensing application was also demonstrated by monitoring the interaction between goat and antigoat immunoglobulin G (IgG) pairs. This integrated high sensitivity biosensor has great potential for medical diagnostic applications.
A highly-sensitive optical waveguide biosensor integrated with microfluidic channels based on silicon-on-insulator (SOI) was investigated in this paper. Experimental results of the label-free detection exhibits this novel biosensor with the superior reliability for quantitative and kinetic measurement of the interaction between biological molecules, dramatically improving the sensitivity due to the Vernier effect induced by cascaded double-microring resonators.
In this article we propose a novel Raman spectroscopic sensor which employs silicon nanowire waveguides for excitation and collection of Raman signal, and an integrated micro-ring resonator as a filter. Preliminary experimental results show that the extinction ratio of the filter including the ring resonator together with the grating coupler is more than 60 dB and the total insertion loss from the laser to the detector is less than 10dB. Theoretical calculations indicate that this high stray light rejection of the filter allows the observation of Raman signal at frequency as low as 4 cm-1 . By employing the evanescent field of the silicon waveguide as excitation and collection of Raman signal, along with the integration of the filter and potentially a tunable semiconductor laser and the detector, a miniaturized Raman spectroscopic sensor can be realized on SOI platform