Innovative Integration of Dual Quantum Cascade Lasers on Silicon Photonics Platform.

Area of Science:

• Photonics
• Quantum Cascade Lasers
• Silicon Photonics

Background:

• Mid-infrared spectroscopy requires compact, integrated light sources.
• Traditional free-space laser modules are bulky and costly.
• Hybrid integration of lasers on silicon photonics platforms is challenging.

Purpose of the Study:

• To demonstrate the first hybrid integration of dual distributed feedback quantum cascade lasers (DFB-QCLs) on a silicon photonics platform.
• To develop a miniaturized, cost-effective mid-infrared light source for portable spectroscopy.

Main Methods:

• Utilized a 3D self-aligned flip-chip assembly process with predesigned QCL waveguide fiducials for sub-micron accuracy.
• Achieved laser oscillation at 7.2 μm with a threshold current of 170 mA at room temperature (pulsed mode).
• Measured sub-milliwatt optical output power at 15 °C (continuous wave) after on-chip beam combining.

Main Results:

• Demonstrated successful hybrid integration of dual DFB-QCLs on silicon photonics.
• Achieved laser oscillation at 7.2 μm with efficient room-temperature operation.
• Miniaturized the light source by 100x compared to traditional modules, with low beam divergence (2.88/1.84 mrad).

Conclusions:

• The 3D self-aligned flip-chip process enables accurate integration of DFB-QCLs on silicon photonics.
• This approach significantly reduces size and cost, paving the way for portable mid-infrared spectroscopy.
• The developed light source is suitable for compact, high-performance sensing applications.