The Design Of Receiving System In Optical Waveguide Phased Array Radar

Optical phased array beam scanning method is different from the traditional means of mechanical method, it can finish no inertia addressing quickly. Scanning devices based on optical phased array need lower driving voltage, power generation is relatively small,and have high scanning speed, scanning angle.Optical phased array devices have potential for development. Waveguide electro-optical scanning phased array system’scanning frequency is up to the MHz range, and its large scan angle and fast scanning speed makes it difficult to design the receiving system, the receiving system based on waveguide phased array scanning device has not yet been completed, so that the receiving system under design of this study on the practical application of the laser waveguide phased array radar has great significance.For waveguide phased array scanning system, this paper designs two receiving systems based on direct detection and heterodyne detection method. First, the direct detection method, for background noise generated by the strong background light, reducing the FOV of optical receiver system effectively suppresses background noise; for larger scan angle of the scanning system, use a multi-aperture optical receiving system; select an APD photodetector for the weak echo signals, with the Zemax software, designs a receiving optical system with a single field of 1°,the design considers noise outside, the receiving system can be used at daytime outdoor environment.Secondly, the paper designs heterodyne detection methods for waveguide phased array scanning system. In order to achieve a large FOV, use the airy method; in order to ensure the local oscillator light and signal light coherence, use the same narrow-linewidth laser.Finally, analyze the signal to noise ratio of direct detection and heterodyne detection, compare two methods, the results show heterodyne detection method have a high capacity for detecting weak signals. But to more complex conditions, direct detection is more simple, more stable and reliable, but in direct detection, the detector can not distinguish between the signal light and the background light, therefore it does not used to detect the weak light.