Theoretical And Experimental Study On The Conical Refraction Of Crystal And The Conical Reflection Of Annular Substrate

With the rapid development of big data and Internet of Things,the high bit rate and high capacity transmission has attracted more attention of researchers in modern communication systems.In the field of dynamic signals transmission,multi-channel fiber optic rotary joint(FORJ)is usually used to realize optical signals transmitting.And the multiplexing technology of optical code division multiple access is usually used to transmit the long-distance multichannel optical signals.Sometimes,along with optical signals transmission,some objects like oil,water,gas and so on are also needed to transfer across the rotating interface.Thus,a hollow optical fiber rotary joint can meet the demand of this objects transform.The phenomenon of conical refraction of biaxial crystal and conical reflection of annular substrate has been studied in this paper for the requirements of multi-channel and hollow FORJ.The reversed effect of conical refraction was studied based on the polarization characteristics of conical refraction,and a scheme was proposed in designing new type of hollow multi-channel FORJ is designed and analyzed using the reversed effect of conical refraction.A hollow annular substrate made up of planer and conical surface was designed based on the conical reflection theory.The circular transmission of the light beam in the annular substrate was discussed.These above researches are of great significance to the development of hollow multi-channel FORJ.Main work of this paper:1.Based on the transmission properties of light beams in biaxial crystal,the diffraction theory of conical refraction has been analyzed.The relationship between the intensity of conical refracted light and the axial position has been analyzed.The intensity of conical refraction beam was simulated using Matlab.And the polarization distribution of conical refraction was discussed.The theory of conical refraction with annular beam has been established.A special polarizer composed of eight polarizers with different polarization orientations was designed to modulate the conical refraction of annular beam.2.The theory of conical refraction for two cascaded crystals has been deduced.The results of theoretical simulation and experiment show that when the two crystals have the same pseudovector,the pattern of conical refraction will be degenerated into one pair rings.When the two cascaded crystals have the same length and opposite pseudovector,the conical refraction will be transformed into a spot which was same as the input beam,and we call this phenomenon as reversed conical refraction.A hollow multi-channel FORJ has been proposed based on the reversed effect of conical refraction.3.Based on the theory of conical reflection,a hollow annular substrate composed of planer and conical surface has been designed.The propagation path of the beam in the annular substrate was calculated and a constraint conditions among the structural parameters has been deduced.The appropriate values of parameters were given by analyzing the relationship between them.The propagation of single-channel and multi-channel beams reflected in the annular substrate has been tracked by LightTools respectively.The corresponding experimental system was established,and the transmitting performance has been tested.The results of optical tracing and actual experiment were in agreement to the theoretical results.The results verified the applicability of the theory proposed in this thesis,and also proved the feasibility of applying the annular substrate into hollow FORJ.