Source: ResearchGate

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In-band Pumping in Photonics

Introduction

In-band pumping is a technique used in optical pumping, commonly employed in lasers and optical amplifiers, especially in solid-state lasers. This method involves utilizing an absorption transition that starts at the lower laser level manifold and ends at the upper laser level manifold.

Working Principle

The absorption and emission bandwidths are substantial due to the multiple Stark levels in each manifold. The rapid thermalization of electrons in each manifold leads to thermal equilibrium. In in-band pumping, the pump light is absorbed while there is gain for the laser or signal light, resulting in efficient energy transfer.

Applications

In-band pumping is frequently used in fiber lasers and amplifiers, offering advantages such as high power conversion efficiency and low heat load. It is commonly employed in ytterbium-doped, erbium-doped, thulium-doped, and neodymium-doped laser systems.

Consequences and Effects

In-band pumping can impact the performance of the laser or amplifier in various ways. It results in a small quantum defect, limited upper-state population, and increased noise figure. By adjusting the pump wavelength, one can optimize gain and noise figure, albeit with trade-offs.

Examples

Examples of in-band pumping include ytterbium-doped fiber amplifiers and lasers, erbium-doped amplifiers and lasers, thulium-doped devices, and neodymium-doped lasers. Each type of laser system has specific characteristics and benefits associated with in-band pumping.

Conclusion

In-band pumping is a versatile technique that plays a crucial role in enhancing the performance of various types of lasers and amplifiers. By understanding the principles and applications of in-band pumping, researchers and engineers can optimize the efficiency and output characteristics of photonics devices.

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