Source: TOPTICA Photonics AG

The Power of Tapered Laser Diodes

Introduction

Single-mode laser diodes are known for their high beam quality but limited optical power output. In contrast, broad area laser diodes offer higher output powers but with reduced beam quality. Tapered laser diodes, also known as high brightness laser diodes, aim to combine high output power with high beam quality.

Operation Principle

Tapered laser diodes have a semiconductor chip design similar to tapered amplifier diodes. The key difference lies in the end reflections: while tapered amplifiers minimize reflections to prevent laser operation, tapered laser diodes utilize end reflections to enable lasing without external optical feedback. By integrating a Bragg grating, the emission wavelength can be selected and the emission linewidth reduced.

Tapered Diode Bars

Some diode bars are made from tapered laser diodes instead of broad area laser diodes, resulting in improved beam quality and higher radiance. Techniques like beam combining further enhance radiance, such as spectral beam combining where emitters operate at slightly different wavelengths.

External-cavity Diode Lasers

External-cavity diode lasers can utilize tapered amplifiers as the gain medium, offering flexibility and control over the laser output characteristics.

Conclusion

Tapered laser diodes represent a significant advancement in laser technology, providing a balance between high output power and superior beam quality. With ongoing research and development, these devices continue to play a crucial role in various applications requiring precise and powerful laser beams.

Source: Ferdinand-Braun-Institut
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