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An organically doped sol−gel optical fiber pH sensor based on silica-entrapped α-naphtholphthalein, is described. The absorption-based device, pumped with a red He−Ne laser, exhibits a dynamic range of 100% change between pH 4 and 11. The design and setup are simple and low cost, and the recladded optical fiber probe is easily replaceable.

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Abstract.We have investigated the effect of the gate voltage on spin relaxation in an Al 0.3 Ga 0.7 As/GaAs/Al 0.3 Ga 0.7 As heterostructure. The study is motivated by a recent proposal for a non-ballistic spin field effect transistor that utilizes the interplay between the Rashba and the Dresselhaus spin-orbit interaction in the device channel. The model, which utilizes real material parameters, in order to calculate spin dynamics as a function of the gate voltage has been developed. From the obtained results we define the efficiency of the spin polarization and spin density modulation. The estimated modulation of the spin polarization at room temperature is of the order of 15-20%. The results show that the effect is not sufficient for device applications. However, it can be observed experimentally by optical pulse-probe techniques.

ilAbstract. We measured the response of short FBGs to a weak planar shock wave. The combined effect of the Photo-Elastic effect and the FBG strain was estimated theoretically depending on its orientation with respect to shock front (for 1550 nm FBG, parallel: 0.9 nm/kbar, perpendicular: -1.4 nm/kbar). The experimental results imply that the FBG/fibre survives for more than 1 μs at 5 kbar shock stress, and that our assumptions about the FBG behaviour under dynamic loading are valid, though more work is needed to fully quantify the effect.

Methods are described for the termination and connection of optical fibres embedded into composite materials intended for structural airframe applications. The methods developed enable connection via standard optical fibre communications hardware to monitoring instrumentation, and interconnection to other composite parts. The connection system is designed to be sufficiently robust to withstand the rigours of the composite material manufacturing process, the aircraft assembly line and routine service.