Dual-wavelength locking technique for coherent 2-µm differential absorption lidar applications

Area of Science:

• Atmospheric Science
• Laser Spectroscopy
• Remote Sensing

Background:

• Differential absorption lidar (DIAL) is crucial for atmospheric measurements.
• Accurate measurement of water vapor and wind velocity profiles is essential for weather and climate studies.
• Existing DIAL techniques face challenges in achieving simultaneous, high-precision measurements.

Purpose of the Study:

• To develop and validate a dual-wavelength locking technique for coherent 2-µm DIAL systems.
• To enable simultaneous measurement of water vapor (H2O) and radial wind velocity profiles.
• To achieve high wavelength stability for improved measurement accuracy.

Main Methods:

• Utilized a dual-wavelength locking technique for a coherent 2-µm DIAL system.
• Stabilized two wavelengths using sidebands of an electro-optic modulated laser locked to a CO2 absorption line.
• Selected specific wavelengths (2050.550 and 2051.103 nm) to minimize environmental influences.

Main Results:

• Achieved long-term wavelength stability of <0.2 pm (14 MHz) for both locked lasers.
• Demonstrated the capability to measure H2O concentration with a systematic error <5% below 5 km altitude.
• Successfully enabled simultaneous profiling of water vapor and radial wind velocity.

Conclusions:

• The developed dual-wavelength locking technique is effective for advanced DIAL applications.
• This technique significantly enhances the precision and capability of atmospheric profiling instruments.
• The system meets critical requirements for accurate water vapor measurements in the lower atmosphere.