| Weak laser power detection system, which can detect weak laser power quickly and accurately, is a kind of precise instrument in judging Laser signal transmission attenuation and loss, and play an important role in optical fiber communication engineering, related scientific experiments and teaching. Aimed at better performances of weak laser power detection system in precision, response speed and multiplicity, the methods and techniques of weak laser power detection are studied, fused mechanism of accurate measurement, signal search and monitor tracking are analyzed, and the rules between parameters of detection system are presented. The purpose of this work is to propose weak laser power detection system design scheme. The contents are presented as follows:1,Noise of detection system is researched.On the base of noise sources and noise power spectral density, noise transmission model is established and noise analysis method is analyzed. The results prove that the noise analysis method which can provide theoretical direction to the hardware construction of weak laser power detection system is right.2,A hardware system of detection system is proposed.Technical difficulties of detection system are analyzed. Then, solutions and design scheme of hardware system are present from probe preferences, noise networks matching, magnifying circuits design, gain switching and error cancelling.3,A software system of detection system is programmed.According to the requirements of hardware system, software block diagrams which include gain switching, error cancelling, temperature warning, communication and display of detection system are compiled, and adaptive noise canceller is used in the form of software.4,The error of debugged detection system is analyzed.A weak laser power detection system is debugged. The results prove that the hardware of the weak laser power detection system, which realize -60dBm sensitivity, 70dBm dynamic range and response time of ms level, is feasible and efficiency. |
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