| The sunlight is a kind of green resources. It has the broad application prospect. Many existing sunlight collection and transmission systems have two problems. One is the efficiency of collection system, and the other is the large transmission loss. The fiber transmission loss problem is particularly serious. This paper studies and designs a sunlight collection system and a sunlight transmission system. The transmission part uses hollow Bragg fiber. Because the band of visible light is too wide, this paper uses three kinds of hollow Bragg fiber. These fibers will each transmits red, green, blue light. These lights gathered in the output end of fibers, so this system can achieve the transmission of sunlight. The main contents of this paper are:1. The design of the sunlight collection system, which uses Finel lens for sunlight gathering and use the horizontal coordinate axis tracking method and photo sensitive resistor array tracking method. The sunlight collecting system can be used in sunny and cloudy.2. This paper uses RSOFT software to research and analyze the photonic crystal band gap of hollow Bragg fiber, which is based on the plane wave expansion method. It discusses the effect of dielectric material, the material refractive index and the lattice period on the band gap of photonic crystals. In addition, the paper designs the suitable fiber material and structure to achieve low transmission loss which can transmit red, green and blue light. The research conclusionis using PC and PVDF as the cladding materials, their refractive index are 2.2 and 1.4. The duty cycle PVDF is1/3.3. This paper researches the transmission characteristics of hollow Bragg fiber. It uses COMSOL software to analyze the transmission loss of hollow Bragg fiber which is based on finite element method. Moreover, the paper discusses the effect of lattice period, fiber core diameter and the cladding layer on transmission loss. In the end, this paper achieves the suitable fiber structure for transmission of red, green and blue light. The cladding layer is 5 or more cycles, air core radius is 75 um, and the lattice period of three kinds of hollow Bragg fibers were 1.35 um, 1.05 um, 0.85 um, respectively. The transmission loss is almost 0, so this system can achieve long distance transmission of sunlight.In a word, the research of Bragg hollow fiber provides theoretical and experimental reference for the automatic tracking and long distance transmission of the sun light. |
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