Silicon photonic waveguide sensor

In recent years, there has been growing interest in development of optical waveguide-based sensors for chemical, biological and physical sensing. Sensor designs such as ring resonator, Mach-Zehnder interferometer, and spectroscopy-based waveguide sensors have shown applicability in detection of specific enzymes, proteins, etc. We present the fabrication and characterization of an integrated micro-ring resonator (RR)-based waveguide sensor. The RR sensor was fabricated on an amorphous silicon-on-insulator (SOI) platform by using electron beam lithography. To realize lab-on-a-chip (LOC), polydimethylsiloxane (PDMS) microfluidics was fabricated using soft lithography and integrated with the photonic chip. For characterization, a tunable external cavity laser with 1550 nm center wavelength was coupled to the RR sensor using tapered fiber. A single mode fiber was used to couple output power from the RR sensor to a photodetector. The RR sensor responsivity was analyzed by measuring the relative resonance shift with different concentrations of saline solution.