High temperature operation of far infrared (λ ≈20 µm) InAs/AlSb quantum cascade lasers with dielectric waveguide

Area of Science:

• Optics and Photonics
• Semiconductor Devices
• Mid-Infrared Technology

Background:

• Quantum cascade lasers (QCLs) are crucial for mid-infrared (MIR) applications.
• High-temperature operation and efficient waveguide design are key challenges in QCL development.
• InAs/AlSb material systems offer potential for advanced QCL performance.

Purpose of the Study:

• To demonstrate high-temperature operation of QCLs emitting at 20 µm.
• To investigate the performance of a plasmon-enhanced dielectric waveguide for QCLs.
• To analyze the optical gain and threshold characteristics of the fabricated devices.

Main Methods:

• Fabrication of QCLs using InAs/AlSb material system.
• Design and implementation of a low-loss plasmon-enhanced dielectric waveguide with doped InAs cladding and spacers.
• Characterization of laser performance, including threshold current density and output power, at various temperatures.

Main Results:

• Successful operation of QCLs up to 80°C at a 20 µm emission wavelength.
• Low threshold current density of 4.3 kA/cm² for 2.9-mm-long devices at room temperature.
• Peak output power of 7 mW at room temperature, indicating high optical gain and effective management of free carrier absorption.

Conclusions:

• The developed InAs/AlSb QCLs with plasmon-enhanced waveguides exhibit excellent high-temperature performance.
• The device design effectively overcomes free carrier absorption, enabling high optical gain.
• These findings pave the way for robust MIR QCLs operating under demanding thermal conditions.