Transverse-mode control in vertical-cavity surface-emitting lasers via a patterned phase aperture.

Area of Science:

• Optics and Photonics
• Semiconductor Lasers

Background:

• Vertical-cavity surface-emitting lasers (VCSELs) are crucial for optical communication.
• Achieving single-mode operation in VCSELs is essential for high-performance applications.
• Mode discrimination is key to controlling laser output characteristics.

Purpose of the Study:

• To numerically analyze transverse-mode discrimination in VCSELs with patterned phase apertures.
• To investigate the impact of aperture geometry on mode selection and beam quality.
• To quantify the enhancement in mode discrimination achieved by phase apertures.

Main Methods:

• Numerical simulation of VCSELs incorporating patterned phase apertures.
• Calculation of the two lowest-order transverse modes.
• Expansion of modes in Laguerre-Gaussian basis for power distribution and beam propagation factor analysis.

Main Results:

• Mode selection is significantly influenced by the aperture's size and symmetry.
• The beam propagation factor and power distribution of different modes were studied.
• A maximum mode discrimination enhancement of threefold was observed with a specific phase aperture compared to no aperture.

Conclusions:

• Patterned phase apertures offer an effective method for enhancing transverse-mode discrimination in VCSELs.
• Aperture design parameters critically determine the degree of mode selectivity.
• The findings provide insights for designing high-performance, single-mode VCSELs.