Source: Ferdinand-Braun-Institut
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Understanding Photonic Crystal Surface-Emitting Lasers

Basic Architecture and Operation Principles

Photonic crystal surface-emitting lasers (PCSELs) utilize a two-dimensional photonic crystal structure as the lateral cavity. The active layer beneath this structure provides laser gain through stimulated emission. The laser is pumped using metallic electrodes, and an optically transparent cladding layer surrounds the structure. A distributed Bragg reflector may be integrated for enhanced power extraction.

Design and Fabrication

PCSELs are fabricated using methods like metal–organic chemical vapor deposition (MOCVD) for epitaxial semiconductor growth. The photonic crystal structure is optimized for specific mode structures, utilizing a photonic band structure to achieve single-mode operation with well-defined polarization and beam shape.

Comparison with Other Lasers

Compared to vertical-cavity surface-emitting lasers (VCSELs) and vertical external-cavity surface-emitting lasers (VECSELs), PCSELs offer higher single-mode output powers due to their larger active areas. They can achieve high continuous-wave output powers and exhibit low beam divergence, making them suitable for various applications.

Possible Applications

PCSELs are attractive for applications like LIDAR, optical data transmission, laser material processing, and pumping solid-state lasers. Their high beam quality, modulation capabilities, and potential for high peak powers make them versatile in different fields.

Beam Steering and Control

PCSELs can be modified to produce multiple output beams in different directions and offer rapid beam steering capabilities. The output beam shape and polarization can be tailored by configuring the lattice structure, allowing for the generation of specialized beam types like cylindrical vector vortex beams.

Conclusion

Photonic crystal surface-emitting lasers represent a promising technology with unique capabilities for high-power, single-mode laser operation. Their design and fabrication allow for tailored beam characteristics, making them valuable for a range of applications requiring high beam quality and modulation speeds.

Source: Weierstrass Institute
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