Source: ResearchGate

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Gain Narrowing in Lasers and Amplifiers

Introduction

Gain narrowing is a phenomenon that occurs when light with a certain optical bandwidth is amplified in an optical amplifier medium with a limited gain bandwidth. This leads to a reduction in the optical bandwidth, resulting in a narrower optical spectrum.

Effects in Mode-locked Lasers

In mode-locked lasers, gain narrowing compresses the optical spectrum of ultrashort pulses, affecting the pulse duration. This phenomenon influences the achievable pulse duration by balancing pulse stretching via gain narrowing and pulse shortening by the modulator.

Effects in Ultrafast Amplifiers

Gain narrowing is crucial in high-gain amplifiers used for very short pulses. For example, regenerative amplifiers amplifying few-cycle pulses must be optimized to prevent significant narrowing of the pulse spectrum. Using a broadband gain medium and minimizing intracavity losses are essential strategies to mitigate gain narrowing effects.

Conclusion

Understanding gain narrowing is vital in the design and optimization of lasers and amplifiers for applications requiring ultrashort pulses. By managing gain bandwidth and minimizing losses, engineers can achieve optimal performance and pulse duration in these systems.

Source: Fosco Connect
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