Source: MDPI
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Understanding Mode Hopping in Lasers

What is Mode Hopping?

Mode hopping is a phenomenon commonly observed in single-frequency lasers where the laser can suddenly switch from operating on one resonator mode to another. This results in a quick redistribution of optical power between different modes.

Causes of Mode Hops

External influences such as temperature changes or fluctuations in the laser resonator can trigger mode hops. For example, a shift in the gain medium’s temperature can cause the laser to switch modes as the mode with the highest gain changes.

Consequences of Mode Hops

Mode hops can disrupt continuous wavelength tuning and lead to laser noise, affecting the laser’s performance. The jumps in wavelength caused by mode hopping can result in fluctuations in laser output.

Avoiding Mode Hopping

To prevent mode hopping, lasers with a large free spectral range are preferred. This means a significant frequency spacing between fundamental modes, making it less likely for the laser to switch modes abruptly. Additionally, minimizing external noise influences and employing nonlinearities can help suppress random mode hops.

Conclusion

Understanding mode hopping in lasers is crucial for optimizing laser performance and stability. By addressing the causes and consequences of mode hops, researchers and engineers can work towards developing more reliable laser systems.

Source: arXiv
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