High-responsivity operation of quantum cascade detectors at 9 µm

Area of Science:

• Optoelectronics
• Semiconductor devices

Background:

• Quantum cascade detectors (QCDs) operate at zero bias with low dark current, showing linearity and high saturation.
• QCDs are suitable for heterodyne detection in long-wave infrared (LWIR) free-space optical communication.

Purpose of the Study:

• To mitigate performance limitations of QCDs at longer wavelengths.
• To optimize responsivity and noise behavior by comparing single and multi-period QCD designs.

Main Methods:

• Fabrication and characterization of InGaAs/InAlAs/InP ridge QCDs for 9.124 µm operation.
• Optical waveguide simulations for accurate optical characterization.
• Comparative analysis of single-period and 15-period QCDs.

Main Results:

• Room-temperature responsivity of 111 mA/W for the 15-period QCD.
• Room-temperature responsivity of 411 mA/W for the single-period QCD.
• Demonstrated optimization approach for long-wavelength QCD performance.

Conclusions:

• Single-period QCDs exhibit higher responsivity than multi-period designs at long wavelengths.
• The presented approach effectively optimizes QCDs for LWIR applications.
• Further research can enhance QCDs for advanced optical communication systems.