Response of a PCF-based modal interferometer to lateral stress: Resonant behavior and performance as sensor

•A fiber interferometer with good behavior as lateral stress sensor is presented.•We provide optimization guidelines of the sensor, concerning the interferometer length and the transmission of its splices.•Its response under periodic forces is characterized, face to possible applications of the device as vibration monitor.•Resonances found under periodic forces are well explained by treating the interferometer as an elastic cylinder.•In nonlinear regime, period doubling and other nonlinear behaviors are also observed.