Abstract
This work presents an alternative solution for simultaneous measurement of strain and temperature. The sensing head is formed by a long-period fiber grating combined with a high-birefringence fiber loop mirror resulting in a configuration capable of temperature and strain discrimination. These optical devices have opposite sensitivity responses when a variation of temperature and/or strain is applied. Maximum errors of +/- 0.8 degrees C and +/- 21 mu epsilon are reported over 60 degrees C and 700-mu epsilon measurement ranges, respectively.

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.

Abstract
An optical fibre intensity sensor referenced by stimulated Brillouin scattering is presented. The optical sensor uses Fresnel reflection signal at the sensor fibre end and employs an adequate relationship between Brillouin and Rayleigh scattering and Fresnel reflection to have a referenced optical fibre intensity sensor addressed in reflection.

Abstract
This work presents a stud), of displacement sensing based on a fiber eight geometry shape monitored by an optical time domain reflectometer. The displacement sensor is referenced by Fresnel reflection or by a fiber Bragg grating structure located after the sensor. One of the advantages of the fiber Bragg grating as referencing device is its capability to be multiplexed by a number of displacement sensors in series along the optical fiber. This concept is also demonstrated using two Bragg gratings. (c) 2007 Wiley Periodicals, Inc.

Abstract
In this letter, a new configuration for simultaneous strain and temperature discrimination is, presented using two concatenated high-birefringence (Hi-Bi) fiber loop mirrors. The first loop mirror includes a Hi-Bi photonic crystal fiber, while the second one contains a length of internal elliptical cladding fiber. It is shown that by monitoring the wavelength and optical power of one of the peaks of the system spectral transfer function, it is possible to obtain information that permits the simultaneous measurement of strain and temperature.