Abstract
A system employing optical fibres for electronic speckle pattern interferometry is demonstrated. Single mode optical fibres are used to provide a reference beam and illumination of the object. The Michelson interferometer formed by the reference fibre and the fibre illuminating the target is used to compensate for environmentally induced phase noise. This compensation is achieved by using an electronic servo and a piezoelectric phase modulator to lock the Michelson at its quadrature point.

Abstract
A scheme to frequency multiplex a group of sensors based on all-fiber Michelson interferometers is presented. Lead insensitivity is obtained by using the two fiber leads of the configuration as an extra Michelson interferometer whose differential phase is kept constant by active compensation. Topics concerning the system design, sensor sensitivity, and crosstalk between sensors are investigated. Experimental and numerical computational results are presented.

Abstract

Abstract
A theoretical and experimental investigation, which allows the quantification of the general error function relative to the synthetic-heterodyne signal processing in interferometric fibre-optic sensors, is performed. The implications on the performance of interferometric sensing arrays are addressed. Considering the decrease of the readout phase errors, potentially more favourable implementations of this processing technique are proposed and compared.

Abstract
A review of optical fiber sensing demonstrations based on photonic crystal fibers is presented. The text is organized in five main sections: the first three deal with sensing approaches relying on fiber Bragg gratings, long-period gratings and interferometric Structures; the fourth one reports applications or these fibers for gas and liquid sensing; finally, the last section focuses oil the exploitation of nonlinear effects in photonic crystal fibers for sensing. A brief review about splicing with photonic crystal fibers is also included.

Abstract
A brief review on suspended-core fibers for sensing applications is presented. A historical overview over the previous ten years about this special designed microstructure optical fiber is described. This fiber presents attractive optical properties for chemical/biological or gas measurement, but it can be further explored for alternative sensing solutions, namely, in-fiber interferometers based on the suspended-core or suspended-multi-core fiber, for physical parameter monitoring. © The Author(s) 2012.