Xianxin Jiang

Cascaded silicon-on-insulator double-ring sensors operating in high-sensitivity transverse-magnetic mode

We demonstrate ultrahigh-sensitivity silicon photonic sensors based on two cascaded double-ring resonators operating in transverse-magnetic mode. Both wavelength interrogation and intensity interrogation methods are experimentally investigated and the sensitivities reached 24,300 nm/RIU and 2430 dB/RIU, respectively. We also show that the double-ring sensors can be simply cascaded to realize simultaneous detection of multiple species, which is very promising for low-cost array applications.

High-sensitivity optical biosensor based on cascaded Mach–Zehnder interferometer and ring resonator using Vernier effect

We demonstrate an ultrahigh sensitivity silicon photonic biosensor based on cascaded Mach-Zehnder interferometer (MZI) and ring resonator with the Vernier effect using wavelength interrogation. Experimental results show that the sensitivities reached 2870 nm/RIU and 21,500 nm/RIU for MZI sensor and MZI-ring sensor, respectively. A biosensing application was demonstrated by monitoring the interaction between goat and antigoat immunoglobulin G (IgG) pairs. The measured results show that 1 ng/ml IgG resulted in 0.035 nm and 0.5 nm wavelength shift for MZI sensor and MZI-ring sensor, respectively. This high performance sensor is promising for medical diagnostic applications.

Ultra-Compact Birefringence-Compensated Arrayed Waveguide Grating Triplexer Based on Silicon-On-Insulator

We demonstrate an ultra-compact birefringence- compensated arrayed waveguide grating (AWG) triplexer for application in optical network units (ONUs) based on silicon nanowire waveguides. The cross-order design is employed to cover three operating wavelengths of 1310, 1490 and 1550 nm for the triplexer. The large birefringence of the silicon-on-insulator (SOI) waveguide is compensated by using angled star coupler design in combination with different diffraction orders for TE and TM modes. The device has a small footprint of only 0.18×0.12 mm2. The excess loss for TM polarization for three channels is 3 ~ 4 dB and the crosstalk is better than -18 dB. The polarization dependent wavelength shift (PDλ) is reduced from about 370 nm to less than 2.5 nm for wavelength channels at 1490-1550 nm.

Silicon nanowire waveguide sensor based on two cascaded ring resonators

We report the latest experimental results of cascaded double ring sensor. To improve the sensitivity, nanowire waveguide sensor operating in TM polarization is designed and fabricated, with the help of the e-beam lithography system. The measured transmission spectrum shows good agreement with theoretical analysis.

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-on-insulator double-ring sensor operating in transverse-magnetic mode

We report the experimental results of a highly sensitive silicon photonic biosensor based on two cascaded ring resonators operating in transverse-magnetic mode. The sensitivities of wavelength interrogation method and intensity interrogation method reach 24,300 nm/RIU and 2,430 dB/RIU, respectively.

Ultra-compact arrayed waveguide grating triplexer based on silicon-on-insulator platform

We have demonstrated an ultra-compact birefringence-compensated arrayed waveguide grating (AWG) triplexer based on silicon nanowire waveguide. The cross-order design is employed and the device has a small footprint of 0.18×0.12 mm2. The normalized losses for TM polarization for three channels are less than 4 dB with the crosstalk better than 18 dB. The polarization dependent wavelength shift (PDλ) is less than 2.5 nm for three channels operating at the wavelength range of 1490-1550 nm by using angled star couplers in combination with different diffraction orders for the two polarizations.

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.