Single-mode high-power interband cascade lasers for mid-infrared absorption spectroscopy

Area of Science:

• Optics and Photonics
• Laser Technology
• Spectroscopy

Background:

• High-sensitivity absorption spectroscopy requires powerful, single-mode light sources in the 3-5 µm range.
• Existing light sources may not meet the demanding power and spectral purity requirements for certain applications.

Purpose of the Study:

• To develop and characterize novel interband cascade lasers (ICLs) for high-sensitivity absorption spectroscopy.
• To achieve high optical output power in a single spectral mode within the mid-infrared (mid-IR) wavelength range.
• To enable precise atmospheric measurements, such as stratospheric hydrogen chloride detection.

Main Methods:

• Utilized interband cascade laser architecture.
• Incorporated second-order laterally coupled Bragg gratings for distributed feedback (DFB).
• Employed a double-ridge laser design with optimized top ridge width (3 µm) for optical mode confinement and a wider ridge (9 µm) for current confinement.

Main Results:

• Achieved 20 mW single-mode optical power at room temperature.
• Reached up to 40 mW single-mode optical power at 0 °C.
• Demonstrated operation at the target wavelength of 3.3746 µm with over 34 mW single-mode power for integrated cavity output spectroscopy.

Conclusions:

• The developed interband cascade lasers meet the critical requirements for high-sensitivity absorption spectroscopy.
• These lasers provide a viable solution for demanding applications, including stratospheric gas analysis.
• The device design and performance represent a significant advancement in mid-IR single-mode laser technology.