Tapered Quantum Cascade Laser Arrays Integrated with Talbot Cavities

Area of Science:

• Optics and Photonics
• Semiconductor Lasers

Background:

• Broad area quantum cascade lasers (QCLs) face beam quality degradation at high power outputs.
• Achieving high power and good beam quality simultaneously is a key challenge in QCL development.

Purpose of the Study:

• To demonstrate a tapered QCL array integrated with a Talbot cavity.
• To achieve fundamental supermode operation for improved beam quality and power scaling.

Main Methods:

• Integration of a tapered QCL array with a Talbot cavity.
• Investigation of supermode operation based on cavity configuration.
• Characterization of far-field beam divergence and output power.

Main Results:

• Fundamental supermode operation achieved with taper straight-end connected to Talbot cavity.
• Near diffraction-limited beam divergence of 2.7° for the fundamental supermode.
• Output power approximately three times higher than a single-ridge laser for a five-element array at 4.8 μm.
• High-order supermode operation observed when taper-end connected to Talbot cavity.

Conclusions:

• Talbot cavity integration enables fundamental supermode operation in tapered QCL arrays.
• This approach enhances beam quality and power output for mid-infrared QCLs.
• Cavity design critically influences supermode selection in QCL arrays.