Transverse mode control in high-contrast grating VCSELs

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Nanophotonics

Background:

• Vertical-cavity surface-emitting lasers (VCSELs) are crucial optoelectronic devices.
• Achieving stable single-mode operation in VCSELs is essential for many applications.
• High-contrast gratings (HCGs) offer a promising approach for advanced VCSEL design.

Purpose of the Study:

• To conduct a comprehensive numerical analysis of HCG VCSELs emitting at 0.98 μm.
• To investigate the impact of non-uniform grating geometry on VCSEL modal behavior.
• To explore the potential of HCGs for achieving 3D selective optical confinement and single-mode operation.

Main Methods:

• Utilized a three-dimensional, fully vectorial optical model for simulation.
• Analyzed a wide range of geometrical parameters for the non-uniform grating.
• Investigated modal behavior and light confinement characteristics.

Main Results:

• Demonstrated that optimized HCGs provide selective 3D confinement of the fundamental mode.
• Showed that HCGs effectively discriminate against higher-order modes by expulsion.
• Identified a design enabling single-mode operation across a broad current range.

Conclusions:

• The proposed HCG design facilitates robust single-mode operation in VCSELs.
• This approach offers potential for enhanced single-mode output power.
• The HCG design provides 3D selective optical confinement with relatively simple fabrication.