Quantum cascade lasers with Y₂O₃ insulation layer operating at 8.1 µm.

Area of Science:

• Semiconductor devices
• Optoelectronics
• Quantum cascade lasers

Background:

• Silicon dioxide (SiO2) is a standard insulation layer in quantum cascade lasers (QCLs).
• SiO2 exhibits a significant absorption peak between 8 to 10 µm, which can impede QCL performance in this wavelength range.
• Alternative insulation materials are needed to optimize QCLs for specific spectral regions.

Purpose of the Study:

• To investigate the feasibility of using yttrium oxide (Y2O3) as an alternative insulation layer in diode-current QCLs (DC-QCLs).
• To demonstrate lasing operation in a DC-QCL utilizing Y2O3.
• To perform a 2D numerical analysis of the absorption coefficient in DC-QCL structures with varying parameters.

Main Methods:

• Fabrication of a DC-QCL structure employing Y2O3 as the insulation layer.
• Experimental demonstration of lasing operation.
• 2D numerical simulations to analyze the absorption coefficient based on insulating materials, waveguide width, and mesa angle.

Main Results:

• Successful demonstration of lasing operation in the DC-QCL at a wavelength of approximately 8.1 µm.
• Yttrium oxide (Y2O3) proved to be a viable alternative insulation material, avoiding the problematic absorption band of SiO2.
• Numerical analysis provided insights into the impact of structural parameters on the absorption characteristics.

Conclusions:

• Yttrium oxide (Y2O3) is a suitable material for insulation layers in DC-QCLs, enabling operation around 8.1 µm.
• The use of Y2O3 circumvents the absorption limitations associated with SiO2 in this spectral range.
• The study highlights the importance of material selection and structural design for optimizing QCL performance.