Weak fiber Bragg grating array has been theoretically analyzed by the transfer matrix method and coupled-mode theory. Fig.1 gives the analysis diagram of weak fiber Bragg grating array Through the mathematical operation, the simulation model of the Weak Fiber Bragg Grating Array is obtained. Numerical predictions of the effects of distributed weak Bragg gratings on the reflection spectra of such a grating are calculated. This fiber with several random distributed weak Bragg gratings has been fabricated. In this paper, the number of peaks in the reflection spectrum increases significantly as the number of gratings increases, and the intensity of reflection increases.These predictions are compared with experimentally measured spectra of the random distributed weak Bragg gratings, the reflection spectra of the weak grating array are measured with an AQ6370 optical spectrum analyzer with a 0.02 nm resolution, A good agreement between the theoretical predictions and the experimental results was obtained. From comparing the experimental results to the simulation results, we figured that transmission peaks have good agreements; the central wavelength of reflection spectra of the weak Bragg grating array about simulation result is 1551.05 nm. We found that when the position and size are changed simultaneously, the reflection spectra of the weak grating Bragg array can be predicted. the number of gratings has a significant effect on the number of reflection peaks, and the larger the number of gratings, the greater the number of reflection peaks. We think it maybe because the light propagates back and forth in the grating and so on.
Proc. SPIE. 8418, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Smart Structures, Micro- and Nano-Optical Devices, and Systems
High temperature pressure pipes were widely used in the chemical, oil companies and power plants, but the pipe burst incidents occurred from time to time, which had caused some damages on people’s lives and property. Thus, in this paper, with the aim to solve this problem, a FBG (FBG: Fiber Bragg Grating) strain gauge structure which consists of three FBGs is designed and fabricated based on the theoretical strain and stress analysis. The strain gauge can be used for the real-time surface strain monitoring of high temperature pressure pipes. In the strain gauge, the elastic hightemperature alloy(10MoWVNb) is chosen as the substrate. The three FBGs with a similar performance are fabricated on the substrate with the high-temperature glue. Among the three FBGs, FBG1 is used for the horizontal strain sensing of high temperature pressure pipes., FBG2 is used for the longitudinal strain of high temperature pressure pipes, and FGB3 is used for temperature compensation. The strain gauge has a feature of high temperature resistance, temperature compensation and two-dimensional strain measurement. The experiment result shows that : the sensing ranges of temperature is 0~300°C, the transverse strain sensitivity is 1.110nm/με, the temperature sensitivity is 0.0213nm/°C; The longitudinal strain sensitivity is 1.104nm/με, the temperature sensitivity is 0.0212nm/°C; the temperature sensitivity is 0.0103nm/°C. Therefore, the strain gauge can meet the needs of the high temperature and pressure pipes.
The modified base-catalyzed method and the seed growth method were employed to synthesize Eu(TTFA)3-doped silica
hybrid spheres. The transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and
fluorescence spectrometer were used to characterize the doping particles. The results show that all kinds of as-prepared
particles present the spherical morphology and the smooth surfaces. TEM images reveal that silica hybrid spheres are
monodisperse and have an average diameter of sub-micron. FTIR analyses show that synthesized silica colloidal spheres
mainly consist of 4-fold silaxone rings, including incomplete condensed silanols and incomplete hydrolyzed alkoxy
groups. The hybrid spheres doped with Eu(TTFA)3 prepared by different methods exhibit the characteristic
photoluminescence (PL) of the Eu3+ ions and excellent narrow-line emission characteristic of Eu3+ ions. The existence of
silica matrix has obious effect on the absorption properties of the ligand and slight effect on the emission properties of
The evolution of the gradient force pattern of hyperbolic-cosine-Gaussian beams induced by a three-zone pure phase plate is numerically investigated. The pure phase plate consists of three concentric zones—the center circular zone, the inner annular zone—and the outer annular zone and the phase variance of inner annular zone is adjustable. The results show that the proposed plate may induce tunable gradient force on the particles in the focal region. The optical trap shape is obviously tunable and multiple traps may occur with changing geometrical parameters of the phase plate. An optical trap shift can be induced by changing the phase variance of the inner annular zone portion. The phase plate may be a very promising method of transporting trapped particles and can be used to construct controllable optical tweezers.
Silica spheres doped with Eu(TTFA)3 and/or Sm(TTFA)3 are successfully synthesized by using the modified Stober method (the base-catalyzed method). Transmission electron microscope (TEM) shows that the hybrid particles have spherical morphology and an average diameter of about 210 nm. Energy dispersive spectroscopy (EDS) confirms that the rare-earth (RE) complexes are incorporated into the hybrid spheres. The particles consist of 4-fold siloxane rings as determined by Fourier transform infrared spectroscopy (FTIR). For the samples doped with Eu(TTFA)3 or Sm(TTFA)3, the typical fluorescence spectra of Eu3+ or Sm3+ emissions are detected, respectively. However, for the samples co-doped with Eu(TTFA)3 and Sm(TTFA)3, photoluminescence (PL) shows the absence of Sm3+ emission and reveals the obvious energy transfer from Sm3+ ions to Eu3+ ions. Note that there are energy transfer processes between the ligands and Eu3+ or Sm3+. Therefore, multiple energy transfer processes are achieved within the hybrid spheres. These energy transfer processes maximize the possible fluorescence emission of Eu3+ ion. The lifetimes of the hybrid spheres are also measured. The RE complex/SiO2 hybrid spheres described in this paper may find promising applications in optical devices and materials science.
In this paper, rare earth (Eu3+, Sm3+) binary chelates with hexafluoroacetylacetone(HFA), thenoyltri fluoroacetylacetone (HTTA), and dibenzoylmethide(DBM) were synthesized, respectively. Then the fluorescence properties of the chelates Eu(TTA)3, Eu(HFA)3, Eu(DBM)3, Sm(TTA)3, Sm(HFA)3 and Sm(DBM)3 in benzene were investigated. It was found that the fluorescence peak at 614nm related to the transition of 5D0->7F2 of Eu3+ was the strongest in Eu(TTA)3. Based on this, the concentration (between 0.05-0.5wt.%) influence of Eu(TTA)3 on fluorescence intensity in Eu(TTA)3-doped PMMA was studied. The results showed the fluorescence intensity increases with Eu(TTA)3 concentrations except that no fluorescence peak was detected for 0.05wt.% Eu(TTA)3-doped sample. However, the sharp fluorescence peak accidentally occurs at 614nm when 0.04wt% Eu(TTA)3 and 0.04wt% Sm(TTA)3 were co-doped in PMMA. Further investigation revealed that similar fluorescence enhancement occurred for all samples co-doped with Eu(TTA)3 and Sm(TTA)3. It indicated that Sm(TTA)3 has a strong sensitization effect on the fluorescence of Eu(TTA)3. Besides, it was also found the sensitization effect could be decreased with the increasing Sm(TTA)3 concentrations for a fixed Eu(TTA)3-doped content. Finally, two possible energy transfer mechanisms were analysed.