高速皮秒脉冲光源的研究

发布时间：2018-03-31 02:03

本文选题：量子密钥分发　切入点：分布式反馈激光器　出处：《合肥工业大学》2017年硕士论文

【摘要】：量子保密通信是基于量子力学理论的密码体制,通过“一次一密”的加密方式实现无条件安全的密码系统。由于理想的单光子源难以制备,在实际量子密钥分发(QKD)系统中,使用的是弱相干光源。高速皮秒脉冲光源作为多功能的弱相干态光源,可应用于实际QKD系统实验和测试环境中。本文首先分析了半导体激光器的工作原理和特性,并阐述了产生超窄光脉冲的增益开关原理。基于分布式反馈(DFB)激光器的工作特性和高速皮秒脉冲光源的需求,设计了激光器的硬件驱动电路。主要包括直流偏置电路,窄脉冲驱动电路和温度控制电路,针对直流偏置电路和窄脉冲驱动电路,采用了集成驱动芯片的方案设计。其中,直流偏置电路本质上是压控电流源电路,利用深度负反馈保证输出电流的稳定性。窄脉冲驱动电路包括输入触发电路、窄脉冲产生、调制驱动三个部分。温度控制电路即利用激光器内部的热敏电阻和热电制冷器(TEC),以及外部电路组成闭环反馈系统。光源的单板采用Altera公司的Cyclone III系列的FPGA作为主控,实现芯片的驱动控制、位置式PI温控算法以及UART通信。最后,对单板进行了电磁兼容性的设计。针对光源的两种驱动方案,在不同的工作模式下,进行了光脉冲波形和光谱特性的测试。实验及测试证明,高速皮秒脉冲光源的光脉冲宽度可以达到65 ps,触发频率可以达到1.25 GHz,能满足实际QKD系统中实验和测试光源的性能指标要求。
[Abstract]:Quantum secure communication is a cryptosystem based on quantum mechanics theory, which realizes the unconditional secure cryptosystem by means of "one time encryption". Because the ideal single photon source is difficult to be prepared, it is in the actual quantum key distribution system (QKD). The high speed picosecond pulse light source, as a multifunctional weak coherent state light source, can be used in the experimental and testing environment of a real QKD system. The principle and characteristics of the semiconductor laser are analyzed in this paper. The principle of gain switch for generating ultralow optical pulse is described. Based on the characteristics of distributed feedback DFB laser and the demand of high speed picosecond pulse light source, the hardware driving circuit of laser is designed, which mainly includes DC bias circuit. For the DC bias circuit and the narrow pulse drive circuit, the integrated drive chip is used in the design of the narrow pulse drive circuit and the temperature control circuit, in which the DC bias circuit is essentially a voltage-controlled current source circuit. The stability of output current is guaranteed by deep negative feedback. The narrow pulse drive circuit includes input trigger circuit, narrow pulse generation, The temperature control circuit is composed of the inner thermistor and thermoelectric cooler of the laser and the external circuit to form the closed-loop feedback system. The single board of the light source is controlled by the FPGA of Cyclone III series of Altera Company. The realization of chip driver control, position Pi temperature control algorithm and UART communication. Finally, the electromagnetic compatibility of the single board is designed. The optical pulse waveforms and spectral characteristics are tested. The pulse width of high speed picosecond pulse source can reach 65 psand the trigger frequency can reach 1.25 GHz, which can meet the performance requirements of experimental and test light source in actual QKD system.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN248

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