High directionality of surface radiation for surface emitting distributed feedback lasers

Area of Science:

• Optoelectronics
• Laser Physics
• Materials Science

Background:

• Surface radiation directionality is crucial for optimizing output power and quantum efficiency in grating-coupled surface-emitting distributed feedback lasers.
• Current designs face limitations in achieving high directionality, impacting device performance.

Purpose of the Study:

• To propose and validate a novel structural scheme for significantly improving the directionality of surface radiation in these lasers.
• To provide a design reference for developing high-performance, stable surface-emitting distributed feedback lasers.

Main Methods:

• Fabrication of a second-order grating on the p-side of an epitaxial wafer.
• Integration of a SiO2/Si3N4 multilayer reflector positioned above the grating.
• Strategic design of an intermediate layer to control phase matching between upward and downward diffracted beams.

Main Results:

• The proposed structural scheme achieves a surface radiation directionality exceeding 98%.
• The design effectively redirects upward-diffracted beams, meeting stringent device requirements.
• Phase adjustment via the intermediate layer thickness is critical for maximizing directionality.

Conclusions:

• The developed design offers a viable solution for achieving high directionality in grating-coupled surface-emitting lasers.
• This approach enables enhanced output power and differential quantum efficiency.
• The findings provide a valuable reference for future high-performance laser development.