title: Fiber Bragg grating laser sensor with direct radio-frequency readout.
abstract: A fiber Bragg grating (FBG)-coupled ring laser sensor is demonstrated. In the proposed configuration the interrogating source, the sensing head and the readout instrument are integrated in a single fiber-optic device. An FBG inserted within a bidirectional fiber ring couples the two counterpropagating modes of the cavity, generating a splitting of the resonant wavelengths proportional to the FBG reflectivity. When the cavity gain is brought beyond threshold, the two peaks of the split resonances simultaneously lase, leading to a beat note in the emission spectrum whose frequency tracks any small shift of the FBG reflectivity spectrum. Such a beat note can be simply monitored by a frequency counter, without the need for an optical spectrometer, allowing to significantly reduce size and costs of the sensor setup. The sensing performance compares well to the state-of-the-art thermo-mechanical fiber sensors.
authors.forename: P
authors.initials: P
authors.lastname: Malara
authors.forename: C E
authors.initials: CE
authors.lastname: Campanella
authors.forename: A
authors.initials: A
authors.lastname: Giorgini
authors.forename: S
authors.initials: S
authors.lastname: Avino
authors.forename: G
authors.initials: G
authors.lastname: Gagliardi