Laser current and temperature control circuits have been developed for a distributed feedback laser diode, which is applied as the light source of a tuneable diode laser absorption spectroscopy system. The laser’s temperature fluctuation can be limited within the range of −0.02 to 0.02°C, and good operation stability was observed through 15 hours of monitoring on the emitting wavelength of the laser. Response time of temperature modulation was tested which is suitable for the tuning requirements of gas detection systems. Laser current can be injected within the range from 40 to 80 mA. In addition, a linear power supply circuit has been developed to provide stable and low-noise power supply for the system. The physical principles of laser modulation theory are discussed before experiments. Experiments show that the output wavelength of the laser can be tuned accurately through changing the working current and temperature. The wavelength can be linearly controlled by temperature at 0.115 nm/°C (I = 70 mA) and be controlled by current at 0.0140 nm/mA (T = 25°C). This is essential for the tuneable diode laser absorption spectroscopy systems. The proposed cost-effective circuits can replace commercial instruments to drive the laser to meet the requirements of methane detection experiments. It can also be applied to detect other gases by changing the light source lasers and parameters of the circuits.

中文翻译：

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基于TDLAS技术的分布式反馈激光二极管光谱调制研究

为分布式反馈激光二极管开发了激光电流和温度控制电路，用作可调谐二极管激光吸收光谱系统的光源。激光器的温度波动可控制在-0.02～0.02℃范围内，通过对激光器发射波长的15小时监测，观察到良好的运行稳定性。测试了温度调制的响应时间，适合气体检测系统的调谐要求。可以在 40 到 80 mA 的范围内注入激光电流。此外，还开发了线性电源电路，为系统提供稳定、低噪声的电源。在实验之前讨论了激光调制理论的物理原理。实验表明，可以通过改变工作电流和温度来精确调谐激光器的输出波长。波长可通过温度线性控制在 0.115 nm/°C (I  = 70 mA) 并由 0.0140 nm/mA ( T  = 25°C)的电流控制。这对于可调谐二极管激光吸收光谱系统至关重要。所提出的具有成本效益的电路可以替代商业仪器来驱动激光器，以满足甲烷检测实验的要求。也可以通过改变光源激光器和电路参数来检测其他气体。