Abstract
This work presents a temperature independent strain/load sensor using a highly birefringent photonic crystal fibre loop mirror. The length of the sensing head is 38 centimetres and its corresponding wavelength spacing between two interferometer minima is 8 nm. The obtained strain and transverse load sensitivity were 1.21 pm/mu epsilon and 0.37 nm/Kg/mm, respectively, while is insensitive to temperature (0.3 pm/degrees C).

Abstract
In this work. the LPG-assisted fibre Michelson modal interferometer is studied as a sensing structure to environmental refractive index, temperature and liquid level when coherence addressing and heterodyne interrogation are considered. The effects on measurand sensitivity of the order of the cladding mode excited by the LPG, of the degree c etching of the sensing fibre and of the fibre type used are investigated.

Abstract
Birefringence monitoring of a Hi-Bi fibre under chemical etching is conducted. The Hi-Bi fibre (a bow-tie type) was inserted in a fibre loop mirror and the optical spectral response was measured while chemical etching of the Hi-Bi fibre was taking place. The birefringence of the bow-tie fibre has decreased due to the etching and the wavelength spacing of the fringe minima of the fibre loop mirror has increased.

Abstract
We report on the analysis and experimental validation of the strain sensitivity dependences of a fiber Bragg grating written in standard optical fiber when combined with fused tapers. By controlling the difference between the cross sections of the fused taper and the Bragg grating, the strain sensitivity of the Bragg wavelength can be changed by acting on the gauge length. The strain sensing characteristics of an interferometric structure formed by fabricating a fused taper in the middle of a fiber Bragg grating are also reported. (C) 2007 Optical Society of America.

Abstract
We present a new configuration based on a fiber ring laser sensor with four-wave mixing effect generation for simultaneous measurement of strain and temperature. The fiber ring laser sensor, corresponding to the signal wavelength, is based on an erbium-doped fiber amplifier, a highly nonlinear bismuth-based optical fiber, and a Bragg grating filter. Four-wave mixing is generated when an external pump laser is combined with a ring laser sensor. Two new peaks appear and are named the converted and satellite wavelengths. With efficiency conversion, which corresponds to the optical power ratio between the converted signal and ring laser input signal, and a Bragg wavelength it is possible to discriminate strain and temperature. Maximum errors of +/- 1.8 degrees C and +/- 12 mu epsilon are reported over 100 degrees C and 1000 mu epsilon measurement ranges, respectively. (c) 2007 Society of PhotoOptical Instrumentation Engineers.

Abstract
In this work, a Brillouin fibre laser sensor for strain and temperature discrimination is presented. The fibre laser sensor consists of a Fabry-Perot cavity with 20 m of optical fibre between two Bragg gratings. For the strain measurement, the 20 m were split in half and in 10 m a pre-tension was applied originating two Brillouin peaks. For the temperature measurement all of the sensing head was heated. The resolutions achieved were +/- 1 mu epsilon and +/- 1 degrees C for strain and temperature measurements, respectively.