On-chip wavelength beam combined DFB quantum cascade laser arrays

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Integrated Photonics

Background:

• Quantum cascade lasers (QCLs) are crucial for mid-infrared (mid-IR) applications.
• On-chip wavelength beam combining (WBC) is needed for power scaling and broadband emission from QCLs.
• Existing methods face challenges in miniaturization and maintaining a single output beam.

Purpose of the Study:

• To propose and demonstrate a straightforward architecture for on-chip WBC of QCLs.
• To achieve high power output and multi-wavelength emission from a single integrated device.
• To advance the development of compact, high-power mid-IR laser sources.

Main Methods:

• Monolithic integration of five distributed feedback (DFB) QCLs with an arrayed waveguide grating (AWG) using III-V semiconductor waveguides.
• Precise design of AWG channel wavelengths to match DFB laser emissions.
• Incorporation of an output amplifier and anti-reflection coatings for power enhancement.

Main Results:

• Demonstrated successful on-chip wavelength beam combining of multiple QCLs.
• Achieved a peak output power of 3 W from the best laser element under pulsed operation.
• Obtained at least 1.75 W from other channels, indicating efficient power combination.

Conclusions:

• The proposed architecture is a significant step towards realizing on-chip high-power WBC QCLs.
• This integration enables compact, high-power, and potentially broadband mid-IR laser sources.
• The results pave the way for advanced applications requiring tailored mid-IR emission.