title: High precision measurement of intensity peak shifts in tunable cascaded microring intensity sensors.
abstract: We demonstrate a method to precisely track intensity peak shifts in tunable cascaded double-microring based refractive index sensors. Without modifications, width of the intensity peak of a tunable cascaded microring device limits the precision of peak-shift measurements and thereby the limit of detection of the sensor. We overcome this limitation by using dual harmonic lock-in detection for precisely determining the position of the intensity maximum. Using this modification, we have demonstrated a reduction in the full width at half-maximum (FWHM) of the intensity peak by a factor of over 1300. We show that such a reduction in FWHM of the peak curve can significantly improve the detection limit of a tunable cascaded microring-based sensor.
authors.forename: Prashanth R
authors.initials: PR
authors.lastname: Prasad
authors.forename: Shankar K
authors.initials: SK
authors.lastname: Selvaraja
authors.forename: Manoj M
authors.initials: MM
authors.lastname: Varma