Study On The Formation Of Optical Beam Based On Dispersion Optical Fiber Prism And Its Temperature Characteristics

With the rapid development of science and technology, the requirement of radar applications is growing. To meet the increasing demand, the technology of phased array antenna came into our sight. Phased array antenna can realize beam forming and scanning by controlling the phase delay of microwave signals among different antenna elements in the system. Therefore, it has the advantages of no physical movement, precise beam steering, and high flexibility. Electric phase shifter is commonly used in wideband phased array antennas at present, but traditional electric phase shifter will suffer the instantaneous bandwidth of signal limited by the aperture effect. That affects the performance of phased array antenna system. Therefore, the true time delay technology is one of the effective means to solve this problem. Compared with traditional phased array antenna, the optical controlled phased array antenna using microwave photonic real time delay technology has low signal loss, wide frequency range, strong survival ability and better confidentiality. Therefore optical delay line based on microwave photonic technology has become a key research topic. At present, optical delay line structure that have been reported in foreign countries mainly include ordinary optical fiber delay structure, dispersion optical true time delay structure, micro filter ring delay structure, spatial grating delay structure and delay structures using fiber gratings like Bragg grating and chirped grating. Domestic research started relatively late and is still in the development stage. So in this paper, we design an optical phased array antenna system based on dispersion fiber prism and introduce its structure and mechanism in detail. Meanwhile, we introduce and analyze theories about the temperature characteristic of dispersion fiber prism optical delay line. The designed optical phased array antenna system's optical fiber cutting precision requirement is low while the number of components and the devices needed is small. We also avoid the use of optical switches which can significantly reduce the cost as well as greatly enhance the system's accuracy and performance simultaneously. In order to make a concrete analysis of the performance and visibility of designed system, the parameters of the system is calculated and the system link is simulated by using software Optisystem. Then the beam pointing angle of the system can be calculated by using software Matlab. The simulation proves that the optical phased array antenna system based on the dispersive optical fiber prism can stably work within the range of ±30 degree beam direction in Ka frequency band under the parameter settings, and the beam direction angle shift caused by the wavelength jitter of lnm is about 1.92 degrees. Finally, in the experimental part, the principle of vector network analyzer which is used in the experiment and the related knowledge of system error calibration is introduced. By using the vector network analyzer, the phase frequency curve of the transmission signal in different optical fiber channel was tested and experimental study on the effect of temperature change on beam pointing of optical controlled phased array antenna system was implemented. The maximum difference caused by the temperature change of 1 degree among different channels is 0.63ps. When the beam steering is set with the range of ±3.5 degree, the optical controlled phased array antenna system based on the dispersive optical fiber prism in the Ka frequency band can work stably in the temperature range of ±7.5 degrees Celsius via setting a central temperature by phase adjustment.