Coupling-induced high-sensitivity silicon microring intensity-based sensor

We propose a coupling-induced intensity-sensing mechanism based on a microring resonator. Different from the conventional intensity sensor, the resonator is working under the analyte-induced variable coupling. The coupling coefficients are highly sensitive to changes of the analyte, thus leading to significant analyte-dependent output intensity. This advanced sensing mechanism is proved with a detection limit of 1.23 x 10(-7), predicted based on the coupled-mode theory. By introducing a phase bias in the Mach-Zehnder interferometer, the detection limit may be enhanced further to 4 x 10(-8), which is demonstrated to be up to 1 order of magnitude more sensitive than that provided by comparable conventional sensors. (c) 2011 Optical Society of America