A two-stage amplifier of laser eavesdropping model based on waveguide fiber taper

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