Study On Novel Non-reciprocal Optical Component And Its Application

The change of space environment directly affects the ground social production activities of human beings,and the drastic changes of space electromagnetic environment cause the damage and abnormal operation of spacecraft,navigation and positioning inaccuracy,etc.As an interdisciplinary subject,space environment science and technology is mainly about the detection,research and prediction of space environment and its effects,obtain the information of various space environments through the development and utilization of various detection technologies,and carry out the multi-zone coupling research.Optical technology plays an increasingly important role in the space and atmospheric environment with its advantages of high-sensitivity,high-resolution,high-selectivity,and real-time.The study on the new high performance devices and related key technologies is of great significance for space environment detection,ecological environment perception and global environmental change monitoring and research.Traditional reciprocal optical components suffer:from low transmission efficiency caused by scattering,reflection and interference,and the optical diffraction limit,which limits their further development of high performance.In this paper,the high performance optical functional components are studied.Since the transmission efficiency can be significantly improved by using the one-way waveguide,and the diffraction limit can be broken by surface plasmon polaritons(SPPs);thus we introduced the one-way waveguide and SPPs to the design of the device.Based on the yttrium iron garnets(YIG)-air-metal waveguide structure,three different non-reciprocal optical components are proposed,which provide novel high-performance optical functional devices for the research of space electromagnetic environment detection,including:Firstly,we theoretically analyze and numerically calculate the dispersion properties of the YIG-air-metal structure,showing one-way propagating feature,and investigate the dependence of one-way propagation on external magnetic field.Based on the one-way waveguide,we propose two different types of high-efficiency tunable T-shaped beam splitters with uniform and non-uniform power,and systematically discuss the influence of the frequency,magnetic field,and the position of the YIG rod on the guiding property.It is shown that the transmission efficiency of such a splitter reaches 100%in the lossless case due to the suppression of reflection by the one-way waveguide.By introducing a defect in the junction area,the splitting ratio of the splitter can be gradually tuned by varying the external magnetic field,and large operation bandwidth can be achieved for a given splitting ratio.We further propose a novel beam-scanning periodic leaky-wave antenna(LWA)based on above one-way waveguide.The dispersion relation of the LWA is numerically calculated,showing the one-way propagation and radiation loss feature.Besides,we systematically analyzed the radiation properties of the LWA for different frequency and external magnetic field by combining theoretical and numerical calculations,and discussed the effects of the material loss and the period number on the radiation.It's shown that,our proposed LWA has a unique one-way dispersive property,and its dispersion curve can span the whole light cone without any gap when the energy flow direction of mode remains unchanged,resulting in having large continuously scanning angle;meanwhile,the LWA can exhibit high directivity owing to the suppression of reflection.The results obtained by full-wave simulation are consistent with our theoretical prediction.In addition,the proposed LWA can exhibit frequency-scanning and fixed-frequency scanning by changing the external magnetic field.Finally,we propose a novel broadband and high efficiency energy squeezing structure,analyze its dispersion for different air layer thickness and external magnetic field,and simulate its guiding characteristics for different frequency,magnetic field,and material loss.It is shown that the efficiency of energy squeezing in the proposed waveguide is 100%in the lossless case,and the enhancement of magnetic field is clearly observed.Moreover,we can tune the operating band by changing the magnitude of applied magnetic field.