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In order to improve ability of amplification about optical arrival angle in laser eavesdropping system, and enhance receiving field of view (FOV) of laser eavesdropping system, this paper presents a new multi-stage amplifier laser eavesdropping model based on waveguide fiber taper. First of all, taking about four-quadrant (4QD) laser eavesdropping model as an example, from the theoretical view, analyses factors that, currently, laser eavesdropping system face many restrictive factors during practical applications. Besides, from the receiving FOV and ability of amplification about arrival angle of incoming optical axis angles, systematically analyses advantages of multi-stage amplifier model. What's more, through constructing laser eavesdropping test platform, we demonstrate Signal to Noise Ratio (SNR) of two stage amplification model is eventually promoted to 6–10 dB compared with one amplifying model, especially in low and high audio level, the advantages is more obvious. Keywords: Laser eavesdropping, Waveguide fiber taper, 4QD

CCD sensor can be used as the imaging device in the initial aiming processing for the beacon laser, and can also be used as the detecting device for the communication lasers optical axis alignment error of the targeting captured trace (APT) unit in space laser communication system. In this paper, based on a double-FPGA structure, we proposed technical solutions to realize the imaging CCD sensor driving and the laser spot position detection algorithm for the CX285AL image sensor by using the overall design of the system block diagram. The spot position detection wave door track centroid algorithm for CCD sensor is also studied by using the analysis of laser transmission characteristics of the atmospheric turbulence. The simulation analysis and field tests have been verified the feasibility of this approach.

The structure and performance of several modulation for atmospheric optical wireless communications was studied and was contrasted under an optical wireless communications model with atmospheric optical radiance scintillation channel Firstly, it discusses the conversion relations of symbol error rate and bit error rate from error theory perspectives analysis atmospheric optical wireless communications, Afterwards pulse interval modulation was point out the insufficient, which uses of Maximum Likelihood to calculate bit error rate of digital pulse interval modulation, so pulse state interval modulation in wireless ultraviolet communication was presented and the structure of pulse state interval modulation was described in detail, requirements of the power and the bandwidth for pulse state interval modulation were analyzed and the Euclidian Distance was derived. The research used pulse standard interval width-locked system to compensate pulse delay and the interference of atmosphere.