The concrete may be damaged because there are freeze-thaw cycles between winter and summer in cold regions. Strain is an alternative parameter which can be used to describe deformation. In this paper, the fiber bragg gratings(FBG) were used to concrete safety monitoring. The strain and temperature sensing properties have been studied. The fiber reinforced polymers (FRP) were used for the packaged techniques of FBG sensors. The neural network was applied to temperature compensation for FBG sensors.
The applied field can cause the inversion symmetry of the silicon single crystal is destroyed and disappears. So the silicon produce a second-order nonlinear optical effect. We exhibition electro-optic effect with index ellipsoid method for analyzing along different direction applied electric field. The result can be used to designing silicon electro-optic modulation.
We propose a new method to measure the birefringence changes in bulk crystals based on the typical Sénarmont configuration. The configuration comprises a linear polarizer, a sample, a quarter-wave plate, an analyzer(P.S.C.A). An external modulator is inserted in the experimental Sénarmont setup. We present a complete analysis of the optical response of a Sénarmont setup within Jones formulation. Compared to the conventional configurations. The new method is able to measure with a high accuracy the variations of the birefringence in any crystal.
In this paper, the electro-induced birefringence based on Kerr effect and Franz-Keldysh effect in bulk silicon crystal at
1.3μm wavelengths has been measured. By using Kerr effect, the third-order susceptibility tensor of bulk crystalline
silicon has been calculated.The two independent tensor of silicon X (3) susceptibility can be obtained by
calculation (3) 6.22 (1 2.2%) 10 <sup>-20 </sup>m<sup>2</sup> V<sup>2</sup> and Xxyxy(3) = and xxxx(3) 9.13 (1 ±2.2%) 10<sup>-20 </sup>m2 V 2 = m<sup>2</sup>/V<sup>2</sup>. The research can drive the
silicon utility in the photo-electricity field.
In this paper, the electro-induced birefringence based on Kerr effect and Franz-Keldysh effect in bulk silicon crystal at 1.3µm wavelengths has been measured, and the element of the third-order nonlinear susceptibility tensor, χ<sup>(3)</sup><sub>xyxy</sub>, has been calculated. We find the change of refractive index induced by Franz-Keldysh effect is dependent on the polarization of the probing beam. Moreover, we deduce that the silicon crystal will become a single-axis crystal from an isotropy crystal when a silicon crystal is biased along  crystallographic direction, and the phenomena of birefringence willoccur as long as the light propagate perpendicularly to the optical axis of silicon crystal. In the experiment, we deduced the ifferences of refractive indices induced by Kerr effect and Franz-Keldysh effect were Δn = 5.49 x 10<sup>-16</sup>E<sup>2.5</sup><sub>0</sub> and Δn<sup>/</sup> = 2.42x10<sup>-16</sup>E<sup>2.5</sup><sub>0</sub>