We have recently demonstrated a particularly economic approach to analyze large arrays of microring resonator
(MRR) sensor elements coupled to a single bus waveguide. The sensor elements can be individually functionalized
to specifically promote the accumulation of target molecules. The binding of target molecules to the surface of a
particular MRR results in an increase of its resonance wavelengths which can be measured with high accuracy.
In order to measure the response of the individual MRR from an array to external stimuli, we employ a special
frequency modulation scheme in which each MRR is independently modulated and phase sensitive lock-in detection
is used to filter the respective frequency component from the superimposed complex transmission spectrum
of the bus waveguide. We fabricated test arrays comprising up to 12 MRR coupled to a single bus waveguide.
A silicon nitride based material system was chosen to realize the devices. Each element of an array is equipped
with a platinum heater electrode for thermo-optical modulation. A tunable laser system was used for optical
characterization and a clear readout of the individual MRR resonance frequencies was possible by employing the
modulation scheme above. Furthermore, we demonstrated a bulk refractive index sensitivity of 190 nm/RIU for
a frequency modulated MRR.
With our first results, we point out the large potential for multiplexed label-free detection of diverse bio molecular
compounds. Due to the miniaturization of the multisensor arrays the realization of portable sensor systems will
be feasible.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.