The optical and acoustic fields of stimulated Brillouin scattering (SBS) effect in the As2S3 chalcogenide suspended-core microstructured optical fibers (MOFs) are investigated by the finite-element method (FEM). The optical and acoustic fundamental modes at 1550 nm are analyzed with the core diameters of the MOFs varying from 1.0 to 6.0 μm. For each case, the holes of the MOFs are filled with different materials such as trichlormethane (CHCL3), alcohol and water. When the core diameter is 6.0 μm, the maximum peak intensity of the optical fundamental mode is in the case with air holes, while the minimum value is in the case filled with CHCL3. The ratio of difference is ~0.66%. The minimum peak intensity of the acoustic fundamental mode is in the case with air holes, while the maximum value is in the case filled with water. The ratio of difference is ~0.13%. The same rule occurs in the fiber cores of 4.5, 3.0 and 2.0 μm, where the decreases of ~0.97%, 1.48%, 1.94% for optical field and the increases of ~0.24%, 0.34%, 0.74% for acoustic field are obtained, respectively. When the core diameter is 1.0 μm, ratios of difference for optical and acoustic fields are much higher than those in the cases of 2.0-6.0 μm, which are ~3.55% and 29.13%, respectively. The overlap factors between optical and acoustic fields are calculated, which are changed with the core diameter and the filled material in holes. Our results will be helpful to strengthen or suppress the SBS effect in practical applications.
In order to obtain accurate position of the inner key components in the experimental advanced superconducting tokamak (EAST), a combined optical measurement method which is comprised of a laser tracker (LT) and articulated coordinate measuring machine (CMM) has been brought forward. LT, which is an optical measurement instrument and has a large measurement range and high accuracy, is employed for establishing the precision measurement network of EAST, and the articulated CMM is also employed for measuring the inner key components of EAST. The measurement uncertainty analyzed by the Unified Spatial Metrology Network (USMN) is 0.20 mm at a confidence probability of 95.44%. The proposed technology is appropriate for the inspection of the reconstruction of the EAST.
The temporal actions of free photoelectrons and shallow trapped photoelectrons in the AgBrI-T grain emulsion were obtained with the microwave absorption and dielectric spectrum technique at the same time. The results indicate that the electron trap effect of sensitization center changes from shallow to deep with the increase of sensitization time. When the function of chemical sensitization center is shallow electron trap effect, the decay of electron is slower and the decay time and lifetime of the photoelectron in sensitized sample are longer than that in unsensitized sample because the sensitization center holds back the recombination between the electron and the hole. When the function of chemical sensitization center is deep electron trap effect, the decay of electron is quicker and the decay time and lifetime of the photoelectron in sensitized sample are shorter than that in unsensitized sample because the sensitization center deeply traps the electrons. The optimal sensitization time is gained according to the relationship between decay time of photoelectron and sensitization time.