Source: Lumispot Tech

The Basics of Diode Stacks in Laser Technology

Introduction to Diode Stacks

A diode stack, also known as a diode laser stack, is a collection of diode bars arranged in a stacked formation. These diode bars are typically arranged vertically in a two-dimensional array. The fabrication process involves cleaving linear diode laser arrays from a wafer, attaching them to thin heat sinks, and stacking these assemblies to create a periodic array of diode bars and heat sinks.

Design and Considerations

For optimal beam quality, the diode bars in a stack should be placed as close together as possible. However, efficient cooling necessitates a minimum thickness of the heat sinks between the bars. This spacing can impact the beam quality and brightness of the combined output. Techniques such as spatial interleaving, polarization coupling, and wavelength multiplexing are employed to address these challenges.

Performance and Applications

Diode stacks are capable of delivering high output powers ranging from hundreds to thousands of watts. They are used in various applications such as pumping high-power solid-state lasers and laser material processing. Fiber-coupled diode stacks can output several kilowatts through a multimode fiber. These systems find applications in laser welding, hardening, alloying, and cladding of metallic surfaces.

Electric Supply and Cooling

Diode bars within a stack are typically electrically connected in series. The electrical driver for a stack must provide high drive currents and voltages. Cooling diode stacks is crucial due to the high dissipated power within a small volume. Techniques like microchannel coolers are used for efficient cooling, especially in continuous-wave operation.

Future Developments

The field of diode stacks continues to evolve with advancements in technology. Output powers have increased significantly while costs have decreased. Improvements in device lifetimes and cooling technologies contribute to the overall efficiency and reliability of diode stacks. Ongoing research aims to enhance performance and expand the range of applications for these systems.

In conclusion, diode stacks play a crucial role in high-power laser systems, offering versatility and efficiency in various industrial and scientific applications.

Source: LAS Photonics
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