Broad tuning range, high power quantum cascade laser at λ ∼ 7.4 µm

Area of Science:

• Quantum optics
• Semiconductor lasers
• Mid-infrared photonics

Background:

• Quantum cascade lasers (QCLs) are crucial semiconductor devices for generating coherent light in the mid-infrared spectrum.
• High output power and broad tunability are key performance metrics for QCLs in applications like spectroscopy and sensing.

Purpose of the Study:

• To report a high-power quantum cascade laser (QCL) operating at λ∼7.4 µm.
• To demonstrate excellent temperature stability and a broad tuning range for the developed QCL.

Main Methods:

• Careful design and optimization of the active region and waveguide structure of the QCL.
• Characterization of output power, wall-plug efficiency (WPE), and temperature stability (T0, T1).
• Evaluation of the external cavity (EC) tuning range and far-field mode characteristics.

Main Results:

• Continuous-wave (CW) output power of 1.36 W at 293 K and 0.5 W at 373 K, demonstrating excellent temperature stability.
• High wall-plug efficiency (WPE) of 8% (CW) and 13.6% (pulsed) at 293 K.
• A broad external cavity (EC) tuning range of 280 cm⁻¹ (6.54 µm to 8 µm) in pulsed operation and 226 mW CW single-mode output power at 293 K.

Conclusions:

• The developed QCL exhibits high power, excellent temperature stability, and a wide tuning range, suitable for demanding mid-infrared applications.
• The optimized device design facilitates robust performance across a significant temperature range (283 K to 373 K).
• The QCL's capabilities in both CW and pulsed modes, including single-mode operation, highlight its versatility.