Single-mode, high-power, mid-infrared, quantum cascade laser phased arrays

Area of Science:

• Quantum Cascade Lasers
• Optoelectronics
• Infrared Photonics

Background:

• Quantum cascade lasers (QCLs) are crucial for mid-infrared applications.
• Optical phased arrays (OPAs) enable beam steering and shaping.
• Integrating QCLs with OPAs presents challenges in power and beam quality.

Purpose of the Study:

• To demonstrate a single-mode, 16-channel OPA based on QCL technology.
• To achieve high output power and narrow spectral width at mid-infrared wavelengths.
• To investigate the performance of integrated QCL-OPAs for beam control.

Main Methods:

• Fabrication of an integrated device including a distributed feedback seed, multi-mode interferometer power splitter, and 16-channel amplifier array.
• Utilizing a Y2O3 coating on angled facet termination to suppress self-lasing (<0.1% reflectivity).
• Characterization of output power, emission spectrum, side mode suppression ratio, and far-field distribution.

Main Results:

• Demonstrated single-mode operation with 30 W peak output power at 4.8 µm.
• Achieved an emission spectrum narrower than 11 nm and side mode suppression ratio >25 dB.
• Confirmed uniform phase distribution across the array output via far-field measurements.
• Also demonstrated 20 W output power from a 3.8 µm QCL amplifier array.

Conclusions:

• The developed QCL-based OPA technology enables high-power, single-mode mid-infrared beam generation.
• The integrated design effectively suppresses self-lasing and ensures uniform phase distribution.
• This work advances the potential of QCL-OPAs for various applications requiring precise beam control.