In this study, resonant microcavities in photonic crystal (PhC) waveguides are investigated for biosensing applications.
The device architecture consists of a PhC waveguide with a defect line for guiding the transmission of light. Resonant
microcavities created by changing the radius of a hole adjacent to the defect line are coupled to the PhC waveguide.
Detection is based on shifts in the resonance wavelength observed in the transmission spectra. The PhC waveguide
device is fabricated on silicon-on-insulator (SOI) wafers using electron beam lithography and reactive-ion etching (RIE).
Receptor molecules are attached to the defects in the device by standard amino-silane and glutaraldehyde crosslinking
chemistry. Preliminary results demonstrate successful detection of human IgG molecules as the target at large
concentration levels of 500 μg/ml. Such PhC waveguide devices are advantageous for medical diagnostics and
biosecurity applications as they allow rapid, label-free, and sensitive detection of multiple analytes in a single platform.
Photonic crystal (PhC) microcavities present multiple advantages for rapid, accurate, label-free, and sensitive detection. But their principle of operation (observation of a peak in transmission) makes their integration in serial arrays difficult. Here we report on multiple resonant cavities coupled to a single photonic crystal waveguide. The device configuration consists of a PhC waveguide with a defect line along which light is guided. Several resonant microcavities, created by modifying the radius of a hole adjacent to the defect line, are coupled to the waveguide. This PhC device, operating as a multi-channel sensor, maintains the advantages of the PhC microcavities and allows for serial arrays: Light is globally transmitted through the waveguide, except for the wavelengths corresponding to the resonant modes of the microcavities. The transmission spectrum shows as many dips as there are cavities. Simulations show that the sensitivity of such structures allows the detection of single particles -typically a virus. Preliminary results show the fabrication and characterization of a double-channel structure with small defects as a solvent sensor.