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Enhanced laser heterodyne spectroscopy contributes to the measurement of atmospheric greenhouse gases

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2023-10-25 15:48:05
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The research team led by Professor Gao Xiaoming of the Chinese Academy of Sciences Hefei Institute of Physical Sciences has improved the measurement accuracy of atmospheric greenhouse gases by using erbium-doped fiber amplifier assisted laser heterodyne radiometer.

The study was published in the Journal of Optics and was selected as an editor's selection.

LHR is renowned for its high sensitivity and spectral resolution, and has become the next generation of lightweight satellite payloads. However, during the scanning process, signals measured by heterodyne radiometers often encounter issues such as reduced baseline slope and signal-to-noise ratio, which can affect measurement accuracy.

In this study, researchers developed a near-infrared laser heterodyne spectroscopy detection scheme based on EDFA.
By adjusting the EDFA for automatic power control, researchers successfully amplified and stabilized the power of the local oscillator DFB laser, thereby significantly reducing baseline fluctuations. This optimization significantly improves the accuracy of the processed atmospheric transmission spectrum.

By using EDFA with automatic power locking function, the LHR can be operated in a state dominated by shot noise during scanning. By eliminating errors caused by baseline slope, EDFA assisted LHR significantly improves its performance.

"This optimization enables LHR to operate in a state dominated by shot noise during the scanning process, "said team member Dr. Li Jun.

In the experimental measurement of atmospheric CO, EDFA assisted LHR was used for the transmission spectrum, and the signal-to-noise ratio of the heterodyne signal was increased by three times.

"These results demonstrate the effectiveness of EDFA assisted LHR in achieving higher accuracy and precision in atmospheric gas measurement, "Dr. Li said.

The team stated that this discovery can improve ground level LHR remote sensing and enhance greenhouse gas knowledge and monitoring.

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