homogeneous saturation (original) (raw)

Author: the photonics expert (RP)

Definition: saturation of an absorption or gain, where the shape of the absorption or gain spectrum is not modified

Category: article belongs to category physical foundations physical foundations

Page views in 12 months: 172

DOI: 10.61835/wmb Cite the article: BibTex BibLaTex plain text HTML Link to this page! LinkedIn

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What is Homogeneous Saturation?

If a strong light beam is amplified in a laser gain medium, the gain can be saturated. That saturation is called homogeneous if the shape of the gain spectrum is not modified, i.e., if the relative change in gain (in decibels) is the same at all optical wavelengths.

Homogeneous saturation usually occurs when the finite gain bandwidth is caused by homogeneous broadening. On the other hand, inhomogeneous saturation typically results when different laser atoms or ions exhibit different characteristics, for example due to different lattice sites occupied in a solid-state host medium. However, quasi-homogeneous saturation is also sometimes observed despite inhomogeneous broadening in situations where many different Stark level transitions overlap. For example, some rare-earth-doped glasses (e.g. neodymium-doped phosphate glasses) exhibit quasi-homogeneous saturation, leading to laser operation with relatively low optical bandwidth.

Frequently Asked Questions

This FAQ section was generated with AI based on the article content and has been reviewed by the article’s author (RP).

What is homogeneous saturation in a laser gain medium?

Homogeneous saturation is a type of gain saturation where a strong light beam reduces the gain of a laser gain medium uniformly across its entire gain spectrum. The shape of the gain spectrum is not changed, only its magnitude is reduced.

What causes homogeneous saturation?

Homogeneous saturation usually occurs when the finite gain bandwidth of the laser medium is caused by homogeneous broadening, meaning all active ions or atoms in the medium have the same emission characteristics.

How does homogeneous saturation differ from inhomogeneous saturation?

In contrast to homogeneous saturation, inhomogeneous saturation affects different parts of the gain spectrum differently. This typically occurs when active atoms or ions have varying characteristics, for example due to their location in a solid-state host medium.

What is quasi-homogeneous saturation?

Quasi-homogeneous saturation is a behavior observed in some media with inhomogeneous broadening, such as neodymium-doped phosphate glasses. It happens when many different Stark level transitions overlap, causing the gain to saturate in a nearly uniform manner.

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