Jinyan Song

Intensity-Interrogated Sensor Based on Cascaded Fabry–Perot Laser and Microring Resonator

A highly sensitive integrated optical biosensor based on the cascade of a Fabry-Perot cavity laser and a microring resonator is investigated theoretically and experimentally. The free spectral ranges of the microring and the laser cavity are designed to be about the same in order to apply intensity interrogation. The variation of the refractive index of the fluidic sample results in a large shift in the envelope function of the total transmission spectrum of the sensor, and consequently, a large change in the transmitted power. The simple light-source-integrated sensing scheme achieved a high sensitivity of 1000 dB/RIU in the preliminary experiment, demonstrating its principle and potential for low-cost practical applications.

Microfluidics-integrated cascaded double-microring resonators for label-free biosensing

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.

Design and optimization of a silica waveguide based visible etched diffraction grating with uniform loss

A novel method for designing a silica waveguide based visible etched diffraction grating (EDG) with uniform loss is proposed. The designed 1st-order EDG comprises 121 output waveguides with a 2.5 nm channel spacing at a wavelength range from 400 nm to 700 nm. Using the conventional flat-field design with two-stigmatic-points method, the simulated channel loss non-uniformity of a conventional EDG is 2.66 dB. By changing the central output waveguide position and rotating the angles of grating facets according to an appropriately designed distribution function, the loss non-uniformity is reduced to 1.36 dB and the highest loss of marginal channels is decreased from 2.69 dB to 2.13 dB simultaneously. With a total chip size of 30 mm×16 mm, this visible EDG is suitable for realization of spectrometer-on-chip. The proposed design method can achieve insertion loss uniformity in a wide wavelength range with no additional element or extra fabrication step.

Optical waveguide biosensor based on cascaded Mach-Zehnder interferometer and ring resonator with Vernier effect

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.

Integrated Raman spectroscopic sensor based on silicon nanowire waveguides

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

High-sensitivity silicon photonic biosensors based on cascaded resonators

Silicon photonic biosensors based on cascaded resonators employing the Vernier effect are shown to be capable of greatly increasing the sensitivity. Two implementation schemes are presented, one using two cascaded ring resonators with a broadband light source, and the other by cascading a Fabry-Perot laser with a silicon ring resonator. Simple intensity interrogation schemes are developed to advance the planar waveguide sensor technology towards low-cost practical applications.