Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design

Area of Science:

• Optics and Photonics
• Semiconductor Lasers
• Spectroscopy

Background:

• Quantum cascade lasers (QCLs) are crucial for mid-infrared (mid-IR) spectral access, offering compact, room-temperature, watt-level continuous wave operation.
• Existing wavelength tuning methods for QCLs often rely on external cavities or have limited monolithic tuning ranges, restricting their application scope.

Purpose of the Study:

• To demonstrate a widely tunable monolithic QCL source with a single emitting aperture.
• To achieve broad wavelength coverage in the mid-IR range for enhanced spectroscopic and sensing applications.

Main Methods:

• Integration of an eight-laser sampled grating distributed feedback laser array with an on-chip beam combiner.
• Utilizing a five-core heterogeneous QCL wafer as the gain medium.
• Development of a compact tunable laser system to individually drive lasers and select wavelengths.

Main Results:

• Demonstrated a widely tunable QCL source covering the 6.2 to 9.1 μm wavelength range.
• Achieved rapid, broadband spectral measurement of methane with excellent agreement compared to a standard infrared spectrometer.
• The monolithic laser system operates without moving parts.

Conclusions:

• The developed monolithic, widely tunable QCL technology offers a compact solution for mid-IR applications.
• This advancement opens new opportunities for high-resolution mid-IR spectroscopy and chemical sensing.
• The laser system's broad tuning range and lack of moving parts enhance its utility and reliability.