High-power vertical-cavity surface-emitting laser with an optimized p-contact diameter

Area of Science:

• Optoelectronics
• Semiconductor Devices
• Laser Technology

Background:

• Vertical-cavity surface-emitting lasers (VCSELs) are crucial optoelectronic devices.
• Achieving high power and excellent beam quality in VCSELs remains an active research area.
• Current spreading significantly impacts VCSEL performance, particularly in bottom-emitting designs.

Purpose of the Study:

• To investigate the effect of p-contact diameter optimization on current distribution in 980 nm bottom-emitting VCSELs.
• To enhance the beam quality and optical output power of VCSELs through numerical simulation and experimental validation.
• To analyze the trade-offs in threshold current and output power resulting from p-contact optimization.

Main Methods:

• Numerical simulation of current spreading within a VCSEL structure with an oxide aperture.
• Fabrication and characterization of 980 nm bottom-emitting VCSELs with varying p-contact diameters.
• Far-field pattern analysis to assess beam divergence and sidelobe suppression.
• Optimization of device packaging to maximize optical output power.

Main Results:

• Optimized p-contact diameter achieved a more homogeneous current distribution for a given oxide aperture.
• Far-field divergence angle was suppressed from 30 to 15 degrees for a 600 µm diameter VCSEL.
• No strong sidelobes were observed in the far-field pattern with the optimized p-contact.
• Maximum optical output power reached 2.01 W after optimizing the device packaging.

Conclusions:

• Optimizing the p-contact diameter is an effective strategy to improve current uniformity and beam quality in 980 nm VCSELs.
• The study demonstrates a significant reduction in beam divergence and suppression of sidelobes.
• The optimized VCSEL design, coupled with improved packaging, enables high-power operation up to 2.01 W.