Optical gain in GaAsBi/GaAs quantum well diode lasers

Area of Science:

• Semiconductor physics
• Optoelectronics
• Materials science

Background:

• Gallium arsenide bismuth (GaAsBi) alloys possess unique band structures beneficial for laser performance.
• Auger recombination and inter-valence band absorption are major loss mechanisms in conventional semiconductor lasers.
• Efficient, uncooled lasers are crucial for telecommunications.

Purpose of the Study:

• To experimentally measure optical gain, absorption, and spontaneous emission in GaAsBi/GaAs quantum well lasers.
• To theoretically analyze the optical properties of GaAsBi-based quantum well structures.
• To validate a theoretical model against experimental data for predictive design.

Main Methods:

• Experimental measurement of optical gain, absorption, and spontaneous emission spectra.
• Theoretical modeling using a 12-band k.p Hamiltonian for GaAsBi alloys.
• Analysis of internal optical losses and modal gain.

Main Results:

• Determined internal optical losses of 10-15 cm⁻¹.
• Achieved a peak modal gain of 24 cm⁻¹ (material gain ~1500 cm⁻¹ at 2 kA cm⁻²).
• Experimental and theoretical results showed excellent quantitative agreement.

Conclusions:

• GaAsBi/GaAs quantum well lasers demonstrate potential for highly efficient, uncooled operation.
• Suppression of key loss mechanisms in GaAsBi is experimentally verified.
• The validated theoretical model aids in designing next-generation infrared lasers.