PHOTONIC CHIPS WITH ONE SIDED OPTICAL PORTS SELF ALIGNED TO BIFURCATED FIBERS FOR THE LABEL FREE DETECTION OF BIOLOMECULAR REACTIONS THROUGH THE USE OF INTEGRATED INTERFEROMETERS AND RESONATORS

摘要

The proposed photonic chip and method for the label free detection of biomolecules is based on a photonic integrated circuit with optical inputs and outputs on the same chip side enabling light coupling in and out through a bifurcated fiber. This is achieved by a U turn on the main waveguides so that the same chip edge is receiving and simultaneously emitting. The chip features Mach- Zehnder interferometers or resonators based on planar waveguides. Spectral and resonance shifts occur when the spotted sensing windows are exposed to the analyte solutions. On theses windows the recognition molecules have been previously immobilized. In the case of Broad-Band Mach- Zehnder interferometers the input fiber supplies broad-band light to the input waveguides, this light goes through the interferometer is getting modulated and is fed back through the output waveguides to the output fiber. This fiber is directed to a spectrometer which monitors the spectral shifts induced by the binding reactions on the sensing window of the interferometer. The Mach- Zehnder configuration greatly enhances the spectral shifts and makes possible the use of commercial spectrometers as detectors. The observable in the interferometer case is the phase of the peak of the Fourier transform of the nearly sinusoidal spectrometer signal. In photonic chips with multiple interferometers each interferometer is engineered so that it has its own distinct peak in the Fourier domain and all peaks are independently tracked by monitoring their phases. In the case of resonators, the input waveguides receive light from a tunable laser source through the input fiber, the light interacts with the resonators and is fed to the output fiber through the output waveguides. The output fiber connects to a photodetector. The same main or bus waveguide can have one or more resonators. The laser bias is swept and the sudden changes in the detector signal are monitored. This way the resonance wavelength shifts are related to binding induced effective index changes. In the case of multiple resonators, the bias sweep is wide enough to include all resonators.