Strain-engineered vertical emitting InGaAsSb quantum well lasers at 2-2.4 µm: in-well vs. barrier pumping, silicate...

Area of Science:

• Semiconductor Lasers
• Optoelectronics
• Materials Science

Background:

• Continuous-wave (cw) lasing in GaSb-based membrane external cavity surface emitting lasers (MECSELs) is crucial for short-wave infrared (SWIR) applications.
• Investigating quantum well (QW) strain and pumping methods is essential for optimizing MECSEL performance.

Purpose of the Study:

• To comprehensively study cw lasing in GaSb-based MECSELs operating in the 2.0-2.4 µm range.
• To analyze the influence of QW strain in InGaAsSb-based MECSEL structures using in-well and barrier pumping.
• To improve MECSEL fabrication yield and thermal performance.

Main Methods:

• Fabrication of eight InGaAsSb-based MECSEL structures with varying QW strain.
• Implementation of silicate bonding for improved wafer bonding yield.
• Comparison of in-well and barrier pumping efficiencies and thermal resistance.
• Theoretical calculations of density of states (DOS) and population inversion.

Main Results:

• Silicate bonding increased fabrication yield from <10% to >60%.
• Only compressively strained QWs with >1% lattice mismatch demonstrated lasing.
• In-well pumping achieved a record-low thermal resistance of 0.5 ± 0.1 K/W at 2 µm.
• Slope efficiency decreased at 2.35 µm due to Auger recombination, but in-well design maintained superior thermal performance (0.6 ± 0.2 K/W).

Conclusions:

• Compressive strain is critical for achieving population inversion in GaSb-based MECSELs.
• In-well pumped MECSELs offer a thermally efficient and wavelength-scalable platform.
• These lasers are suitable for SWIR applications like gas sensing, medical diagnostics, and molecular spectroscopy.