Fiber-optic Front-end Laser Warning Device Domain, Frequency Domain Coding Techniques

Laser warning technology is one of the most important technologies of electronic warfare. Laser warning system using optical fiber front end technology can improve the laser-capturing device, reduce electromagnetic interference (EMI) and resist intense laser radiation. This thesis mainly introduces optical antenna arrays and coding method of laser warning system using optical fiber front end technology.Laser beam received by more than two optical antennas can be weighted to get more precise azimuth angle. In this thesis, optical antenna aperture is deduced to ensure that laser beam from any azimuth angle can be received by at least two optical antennas. The operation principle and implementation of time coding of the antennas are represented in the thesis. The weighting formula using waveform area is deduced and aberration calculated by the formula is listed in table. Furthermore the thesis provided a new method to weight the angular by comparing the light intensity which can void complex computation. It had been described for the operation principle and implementation. And angular resolutions got by comparing light intensity are also listed in table.On the pulse frequency encoding of the antennas, the thesis provided the feedback units using multi closed loop delay circuit. The impulse sequence signals from multi closed loop delay circuit has more impulses and the amplitude of impulse sequence signals vary little. So the half width of characteristic frequency is narrow. This method can depress the adjacent-antenna interference. Furthermore it had given the parameters for tow closed loop delay circuits to generate the constant amplitude pulse trains. Experimental system is established according to the parameters and the result is analyzed in detail.