基于FPGA的DFB激光器驱动电路的设计

发布时间：2018-02-11 13:17

本文关键词： FPGA DFB激光器激光器驱动 DDS ATmega16 波长调制　出处：《吉林大学》2013年硕士论文　论文类型：学位论文

【摘要】：分布反馈式（DFB）激光器是一种典型的波长可调谐的激光器，是气体浓度检测中的常用光源。其最大特点是具有非常好的单色性以及非常高的边摸抑制比（SMSR，40-50dB）。在气体浓度的检测中，与一般的检测方法相比，波长调制方法是将正弦波信号叠加三角波信号驱动激光器，利用二次谐波幅度表征气体浓度，输出端检测正弦信号的二次谐波，可使检测灵敏度比直接吸收方法高2-3个量级。而在该技术中，为了使DFB激光器的波长与气体的吸收峰值相互匹配，必须对其波长进行精确调谐。因此，，研究DFB激光器驱动电路具有实用价值。首先，本论文介绍了DFB激光器的工作原理，研究了激光器驱动电路的基本设计思想。重点介绍了可调谐半导体激光吸收谱技术(TDLAS)和波长调制法，提出了依据波长调制法设计激光器驱动电路的总体方案。其次，本论文以ATmega16单片机为核心，设计了驱动电路硬件原理图。DDS系统产生的三角波与正弦波将完成波长扫描和波长调制，由于正弦波和三角波需要叠加，因此，设计了一种同向加法电路。同时，设计了一款基于OP37的压控恒流源电路，完成对激光器的恒流驱动。此外，还设计了按键电路、显示电路和通信电路等。接着，设计了系统软件。首先利用现场可编程门阵列（FPGA）设计直接频率合成器（DDS），结合Quartus II软件对DDS做了仿真。通过频率控制字来调节DDS的输出频率，同时改变ROM中的存储数据可获得所需的任意波形。最后，作为论文的实验环节，采用VHDL语言编写了系统程序，结合Quartus II软件下载至ALTERA公司的FPGA芯片EP2C8Q208C8中，产生了频率为20kHz的正弦波信号以及频率为20Hz的三角波信号。利用模拟负载开展了实验，结果显示，驱动电路产生的恒定电流范围在20mA-100mA。
[Abstract]:Distributed feedback (DFB) laser is a typical laser wavelength tunable light source, is commonly used in gas concentration detection. Its most prominent feature is a very good monochromaticity and very high side mode suppression ratio (SMSR, 40-50dB). In the detection of gas concentration, compared with normal testing methods and the wavelength modulation method is the sine wave superposition triangle wave signal driving laser, using the two harmonic amplitude characterization of gas concentration, the two harmonic output sinusoidal signal detection, the detection sensitivity is 2-3 orders of magnitude higher than direct absorption method. In this technique, in order to make the matching between the absorption peak wavelength and DFB gas laser the tuning of the wavelength must be precisely. Therefore, the research of DFB laser driving circuit has practical value.
Firstly, this paper introduces the working principle of DFB laser, the basic design idea of the laser drive circuit. Mainly introduced tunable diode laser absorption spectroscopy (TDLAS) and wavelength modulation method is proposed according to the design scheme of laser wavelength modulation driving circuit.
Secondly, this paper takes ATmega16 microcontroller as the core design of triangular wave and sine wave driving circuit hardware principle diagram of the.DDS system will complete the scanning wavelength and wavelength modulation, sine wave and triangular wave due to be added, therefore, to design a summing circuit. At the same time, the design of a voltage controlled based on OP37 the constant current source circuit, complete constant current driving of laser. In addition, also designed the key circuit, display circuit and communication circuit.
Then, the system software is designed. Firstly, using field programmable gate array (FPGA) design of direct frequency synthesizer (DDS), combined with Quartus II software DDS to do the simulation. The output frequency of the frequency control word to regulate DDS, and change the stored data in the ROM can obtain the required arbitrarywaveforms.
Finally, as the experimental procedures, using VHDL language program, combined with Quartus II software to download ALTERA's FPGA chip EP2C8Q208C8, the frequency of sine wave signal 20kHz and the frequency of the triangular wave signal of 20Hz. Using the load simulation experiment was carried out, results show that the driving circuit generates a constant current range in 20mA-100mA.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TN248;TP368.1

【参考文献】