The Research And Preparation Of Optical True Time Delay Based On Polymer Waveguide

The traditional phased array radar is restricted by the aperture effect and aperture transit time, so it is difficult to achieve large instantaneous bandwidth at a high scan angle. But when the optical waveguide delay-line is applicable to the phased-array-radar, it has been resolved. The optical waveguide delay-line has also some huge advantages in improving the resolution of radar, the ability to identify, solving multi-objective imaging, coping anti-radiation missiles, simplifying the structure and reducing the volume. The organic polymer material has some advantages, such as the good film-forming properties, low dielectric constant, large electro-optic and thermo-optical coefficient, low loss, simple preparation process, low cost, etc. So it is an ideal material to prepare the optical waveguide delay-line. In this thesis, the almost research work focus on the principle, design, preparation process, test of the optical waveguide delay-line.In this paper, at first, using the beam propagation method and effective index method gives a design and optimization curved waveguide delay lines based on polymer materials. Satisfies the conditions of single-mode transmission waveguide dimensions:width and height all is 4?m. To reduce the bending radius, we need increase the refractive index difference between the core and the cladding. So select the ZPU 13-44 and ZPU 13-46 as the cladding layer and the core layer, their refractive index difference are 0.02. It was found,when the bending radius is greater than 3500?m, the bending loss can be ignored. For improving the integration, minimizing the bending radius is necessary. Therefore, design and lead into the Offset and Trench structure. From the theoretical modeling and experimental data, when the bending radius is 500?m, the offset allows maximum loss reduced by 20%, the trench allows maximum loss reduced by 60%. To further reduce the transmission loss of the optical waveguide, I have done a more in-depth research on reactive ion etching process and found the optimal parameters of etching ZPU series polymer materials:the etching power is 100w, the reaction chamber pressure is 3pa, the etching gas is a mixed gas of oxygen(30sccm) and methane trifluoride(20sccm), the etch rate of this condition is 0.105?m/min. We also try to swing the upper cladding layer early.In this paper, the current more mature ultraviolet lithography and reactive ion etching process used to prepare the polymer curved waveguide delay lines. Through numerous experiments to find the optimum process parameters. At last, have prepared the low-loss polymer curved waveguide delay lines successfully. On this basis, further design a long spiral waveguide delay line, its waveguide length of single helical structure is 17.08cm(the traight waveguide insertion loss is -5.5dB, the end-fire coupling loss is-1.35dB/ surface, the transmission loss is -0.81dB/cm), the double helix structure is 30.76cm(the traight waveguide insertion loss is -5.8dB, the end-fire coupling loss-1.58dB/surface, the transmission loss is -0.76dB/cm), and the length of the straight waveguide is 3.4cm.