Abstract
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.
Highlights
Infrared absorption spectroscopy is widely researched due to numerous advantages including fast response, nonintrusive nature, and sensitive species-specific detection capabilities [1,2,3,4], compared with traditional gas-sensing techniques such as catalyst combustion [5,6,7], electrochemical [8,9,10], and semiconductor [11,12,13]. erefore, gas-sensing systems and sensors based on infrared absorption spectroscopy have been reported by many research groups in recent years, and many related techniques have been developed and improved to achieve high-sensitive sensing ability [14,15,16]
Electric field effect is known as the quantum confined Stark effect (QCSE). ird, temperature effect is widely adopted in Tuneable diode laser absorption spectroscopy (TDLAS) systems
Based on the TDLAS technique, laser current control and temperature control circuits have been developed to control the output wavelength of the laser diode. e wavelength of the laser diode is at 1654 nm, which is applied for methane detection
Summary
Infrared absorption spectroscopy is widely researched due to numerous advantages including fast response, nonintrusive nature, and sensitive species-specific detection capabilities [1,2,3,4], compared with traditional gas-sensing techniques such as catalyst combustion [5,6,7], electrochemical [8,9,10], and semiconductor [11,12,13]. erefore, gas-sensing systems and sensors based on infrared absorption spectroscopy have been reported by many research groups in recent years, and many related techniques have been developed and improved to achieve high-sensitive sensing ability [14,15,16]. Tuneable diode laser absorption spectroscopy (TDLAS) technology is widely used in the field of trace gas detection, among many of the optical detection techniques [17,18,19,20]. DFB lasers are controlled by using laser driver devices that can set the working current and temperature In this way, experiments based on TDLAS are commonly utilizing commercial instruments including laser current drivers and temperature controllers to satisfy the experimental requirements. By utilizing the commercial instruments mentioned above, lasers can be controlled effectively to meet the requirements of gas-sensing experiments based on infrared absorption spectroscopy techniques [26, 27]. Is laser driver is made of self-developed circuits It has the capability of controlling laser temperature, driving current, and modulating essential signals based on the TDLAS technique. The spectroscopy is measured by using the self-developed laser driver and the results are discussed in the end of this paper
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