A multimode interference refractive index （KI） sensor based on the coreless fiber was numerically and experimentally demonstrated. Two identical single mode fibers （SMF） are spliced at both ends of a section of th...A multimode interference refractive index （KI） sensor based on the coreless fiber was numerically and experimentally demonstrated. Two identical single mode fibers （SMF） are spliced at both ends of a section of the coreless fiber which can he considered as the equivalent weakly guiding multimode fiber （MMF） with a step-index profile when the surrounding refractive index （SKI） is lower than that of the coreless fiber. Thus, it becomes the conventional single-mode multimode single-mode （SMS） fiber structure but with a larger core size. The output spectra will shift along with the changes in the SKI owing to the direct exposure of the coreless fiber. The output spectra under different SKIs were numerically studied, as well as the sensitivities with different lengths and diameters of the coreless fiber. The predication and calculation showed the good agreement with the experimental results. The proposed RI sensor proved to be feasible by verification experiments, and the relative error was merely 0.1% which occupied preferable sensing performance and practicability.展开更多
We investigate the spatial coherence of the light generated from high-power multi-chip red LEDs by usmg the van Cittert- Zernike theorem. It is theoretically demonstrated that the light generated from multi-chip LEDs ...We investigate the spatial coherence of the light generated from high-power multi-chip red LEDs by usmg the van Cittert- Zernike theorem. It is theoretically demonstrated that the light generated from multi-chip LEDs evolves into partially coherent light after propagation, and the spatial coherence is increased with the increase of propagation distance. Moreover, the spatial coherence of the light is found to be closely related to the chip distribution of multi-chip LEDs. The distribution of the spatial coherence of the light is experimentally examined by Young＇s double-slit interference. It is found that the experimental results are consistent with the theoretical ones.展开更多
文摘A multimode interference refractive index （KI） sensor based on the coreless fiber was numerically and experimentally demonstrated. Two identical single mode fibers （SMF） are spliced at both ends of a section of the coreless fiber which can he considered as the equivalent weakly guiding multimode fiber （MMF） with a step-index profile when the surrounding refractive index （SKI） is lower than that of the coreless fiber. Thus, it becomes the conventional single-mode multimode single-mode （SMS） fiber structure but with a larger core size. The output spectra will shift along with the changes in the SKI owing to the direct exposure of the coreless fiber. The output spectra under different SKIs were numerically studied, as well as the sensitivities with different lengths and diameters of the coreless fiber. The predication and calculation showed the good agreement with the experimental results. The proposed RI sensor proved to be feasible by verification experiments, and the relative error was merely 0.1% which occupied preferable sensing performance and practicability.
基金supported by the National Natural Science Foundation of China(Nos.60977068and61178015)
文摘We investigate the spatial coherence of the light generated from high-power multi-chip red LEDs by usmg the van Cittert- Zernike theorem. It is theoretically demonstrated that the light generated from multi-chip LEDs evolves into partially coherent light after propagation, and the spatial coherence is increased with the increase of propagation distance. Moreover, the spatial coherence of the light is found to be closely related to the chip distribution of multi-chip LEDs. The distribution of the spatial coherence of the light is experimentally examined by Young＇s double-slit interference. It is found that the experimental results are consistent with the theoretical ones.
