Abstract
A sensor based on a Sagnac topology in reflection is described. The sensor uses the properties of its frequency response in order to obtain a self-referenced signal proportional to the measured signal. The sensor is a versatile structure for the monitoring of static and dynamic physical parameters, which require a small number of optical components and simple signal processing.

Abstract
In this paper we present a novel microbend optical fibre sensor embedded in composite material, which acts as a load cell for structural monitoring in civil engineering. The sensing system is based on a self-referenced fibre optic intensity sensor supported by a Michelson topology with optical feedback. The sensing system is tested in a sand testing bed for different values of load. Results are presented and discussed.

Abstract
An investigation is performed of the characteristics of the self-referencing intensity based Q-type fibre optic sensor using a recirculation loop structure. Both transmissive and reflective configurations are analysed. Via the definition of the measurement parameter (the R parameter) the linearity and sensitivity of the sensor are addressed. Theoretical and experimental results are compared, considering the problem of sensor design and optimization.

Abstract
The development of fiber optical sensor in which the sensing head comprises a long period fiber grating (LPG) whose attenuation peak varies as function of its bending was investigated. Various arc-induced LPGs were fabricated in the spectral region of the optical source. The spectral power evolution was taken from a streched to a bending position with the optical spectrum analyzer. The developed fiber optical sensor demonstrated its capability of micro-displacement measurement.

Abstract
A novel microbend optical fiber sensing head embedded in Carbon Fiber Reinforced Plastic (CFRP) was developed. The sensor demonstrated its capability of measuring applied pressure up to 750 kPa.

Abstract
A sensor for measurement of refractive index in oils was discussed. The sensor comprised a fiber based-device sensing head placed in a self-referenced fiber optic intensity sensor. The sensing head works on the principle of change of the refractive index of the medium that surrounds the unclad portion of multimode fiber. This results in different attenuation of the guided modes that propagate in the fiber. The injection current of the optical source was swept in frequency to obtain the transfer function.