Abstract: An optical fiber sensor includes optical sensor elements, for instance a plurality of multiplexed Bragg gratings, a broadband optical source, an interferometer with at least one polarization-maintaining fiber section with which a birefringence modulator, a signal generator and a receiver are associated. The optical birefringence in the propagation medium, i.e., in the polarization-maintaining fibre, combined with the birefringence of the birefringence modulator, produce in the interferometer the path difference and thereby the interference fringes which, appropriately processed according to the known technique, allow the measurement to be traced. The use of a birefringence modulator associated with the polarization-maintaining fiber allows a high-speed modulation of the interferometer, thus allowing high sampling rates of the sensor without having variations in responsivity depending on the alignment of the sensors with the interferential fringes of the interferometer.

Abstract: An optical fiber sensor includes optical sensor elements, for instance a plurality of multiplexed Bragg gratings, a broadband optical source, an interferometer with at least one polarization-maintaining fiber section with which a birefringence modulator, a signal generator and a receiver are associated. The optical birefringence in the propagation medium, i.e., in the polarization-maintaining fibre, combined with the birefringence of the birefringence modulator, produce in the interferometer the path difference and thereby the interference fringes which, appropriately processed according to the known technique, allow the measurement to be traced. The use of a birefringence modulator associated with the polarization-maintaining fiber allows a high-speed modulation of the interferometer, thus allowing high sampling rates of the sensor without having variations in responsivity depending on the alignment of the sensors with the interferential fringes of the interferometer.

Abstract: Methods and apparatus are provided for switching an optical signal. In one aspect, an optical switching apparatus comprises a first beam splitting apparatus configured to split a first optical input signal into first and second optical signals, wherein the first optical signal has substantially the same polarization state as the second optical signal. The apparatus also comprises a switching matrix comprising a plurality of first outputs of the switching matrix and a plurality of second outputs of the switching matrix, each first output of the switching matrix associated with a respective one of the second outputs of the switching matrix, the switching matrix configured to selectively direct the first optical signal to a selected one of the first outputs of the switching matrix and to selectively direct the second optical signal to the second output of the switching matrix associated with the selected first output of the switching matrix.

Abstract: Methods and apparatus are provided for switching an optical signal. In one aspect, an optical switching apparatus comprises a first beam splitting apparatus configured to split a first optical input signal into first and second optical signals, wherein the first optical signal has substantially the same polarization state as the second optical signal. The apparatus also comprises a switching matrix comprising a plurality of first outputs of the switching matrix and a plurality of second outputs of the switching matrix, each first output of the switching matrix associated with a respective one of the second outputs of the switching matrix, the switching matrix configured to selectively direct the first optical signal to a selected one of the first outputs of the switching matrix and to selectively direct the second optical signal to the second output of the switching matrix associated with the selected first output of the switching matrix.