【Objective】

2

For high-power lasers operating at the 1

060 nm band

edge-emitting semiconductor Laser Diode (LD) offer higher efficiency

lower cost

greater reliability

and smaller size compared with conventional solid-state lasers. However

their output exhibits an asymmetric far-field profile and a relatively large beam divergence angle. The objective of this study is to optimize the waveguide structure of edge-emitting LDs at 1 060 nm using a far-field theoretical model

aiming to improve the far-field beam symmetry

reduce the divergence angle

and achieve quasi-collimated emission.

【Methods】

2

In terms of research methods

this article first analyzes the relationship between the far-field divergence angle of edge-emitting LD and its near-field spots based on the theory of three-layer planar waveguides. Then using Lumerical's Finite-Difference Time-Domain (FDTD) simulation software

the waveguide structure of an edge-emitting LD and its near-field intensity profile are designed

with particular emphasis on specialized microstructures

to improve the far-field characteristics.

【Results】

2

In this paper

a microstructure edge-emitting LD with inclined sidewall slots is designed by using Lumerical FDTD software. The laser operates at 1 060 nm. The structure has a thin graded refractive index layer

a Single Quantum Well (SQW) active layer

and an asymmetric wide waveguide layer. The ridge waveguide near the output facet is uniformly patterned with specially designed oblique sidewall grooves. The simulation results show that the designed ridge waveguide edge-emitting LD obtains a vertical far-field divergence angle of 2.7° and emits near collimation at an angle of ~1°.

【Conclusion】

2

This work demonstrates

through simulation

the feasibility of beam control by tuning the sidewall tilt angle of laser grooves. By optimizing the vertical waveguide structure of the edge-emitting LD and carefully de-signing the groove parameters

a low far-field divergence angle and quasi-collimated output have been achieved.