Source: Laserworld

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The Concept of Slave Lasers in Photonics

A slave laser is a type of laser that emits light at an optical frequency determined by an external master laser, also known as a seed laser, through a process called injection locking. The seed laser is typically a low-noise, single-frequency laser, while the slave laser is a high-power laser. An electronic servo system is commonly employed to maintain the frequency of a resonator mode of the slave laser close to that of the master laser for frequency locking.

Benefits of Injection Locking

Injection locking enables the slave laser to achieve better noise properties compared to trying to directly attain low-noise performance in a high-power laser. When the master laser is not active, the high-power laser would typically emit light over a range of frequencies with higher intensity and phase noise. Injection locking facilitates the production of light on a single frequency with improved noise characteristics. Additionally, a single master laser can drive multiple slave lasers.

Comparison with Optical Amplifiers

While optical amplifiers are an alternative, achieving similar gain levels as with injection locking, especially in high-power amplifiers, can be challenging. Moreover, injection locking tends to offer substantially better noise properties, making it a preferred choice in many applications.

Conclusion

Slave lasers, operated through injection locking, play a crucial role in photonics applications where high-power laser sources with good noise characteristics are required. By leveraging the benefits of frequency locking and noise reduction, slave lasers offer a reliable and efficient solution for various optical systems.

Source: MDPI
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