Analysis of power transfer on multicore fibers with long-period gratings.

The use of long-period gratings (LPGs) to distribute optical power from one core to all the cores in a multicore fiber (MCF) is theoretically analyzed. Simple analytical expressions that describe the mode power's evolution along the LPGs are derived from the coupled mode equations. This study demonstrated the power transfer between cores in a MCF promoted by identical LPGs. Moreover, with this technique, the pump signal can be distributed to all the cores without interfering with the transmission signals.

Evaluation of diamond coatings on optical fibre sensors for biological use.

The inscription of a Fibre Bragg Grating (FBG) in optical fibres allows them to be used as sensors, being capable of decoding small variations of strain; temperature; pressure; loading; bending; or even refractive index, by means of a shift in the reflected wavelength. Nevertheless, broadening their sensitivity and operation range would be desirable. This may be achieved by appropriated fibre coating. Diamond possesses a set of extreme properties, such as high thermal conductivity, hardness and resistance to hazard environments. Furthermore, it is known for its excellent biocompatible response, so it may be suitable to be used as a coating material for biological sensors. In this paper, the results of the optimization process of diamond coatings on optical fibre sensors is presented, considering their potential use for practical biological purposes.

Photonic RF instantaneous frequency measurement system by means of a polarizatio-ndomain interferometer.

A new photonic RF instantaneous frequency measurement system is proposed and experimentally demonstrated. A frequency measurement independent of the optical input power and microwave modulation index is achieved by using the constructive and destructive ports of a polarization-domain interferometer. Experimental tests yield a peak-to-peak frequency error lower than 200 MHz for a frequency range of 1-18 GHz.

Hyperfine and magnetic properties of Fe-Cu clusters and Fe precipitates embedded in a Cu matrix.

Using the first-principles real-space linear muffin-tin orbital method within the atomic sphere approximation (RS-LMTO-ASA) we study hyperfine and local magnetic properties of substituted pure Fe and Fe-Cu clusters in an fcc Cu matrix. Spin and orbital contributions to magnetic moments, hyperfine fields and the Mössbauer isomer shifts at the Fe sites in Fe precipitates and Fe-Cu alloy clusters of sizes up to 60 Fe atoms embedded in the Cu matrix are calculated and the influence of the local environment on these properties is discussed.