Quantum Cascade Laser: a better alternative to CO2 laser for selective laser sintering

CO2 laser is a popular choice for selective laser sintering (SLS) due to its power efficiency.

The wavelength of the light produced by CO2 laser is around 2.5 µm. Most of this light is absorbed by the sintering powder and only a small fraction bounces off its surface, thus leading to efficient heating.

Limitations of CO2 laser

Since CO2 laser produces a fixed wavelength, the surface of the resulting models are rough. This makes it difficult to capture small details. 

Besides, the building speed is low due to vector-type imaging. CO2 laser based selective sintering machines are also expensive due to their physical size, which is dictated by the CO2 optical path.

Due to these drawbacks it isn’t always a suitable choice for all applications.

Working of Quantum Cascade Laser

A quantum cascade laser (QCL) is a solid-state device built from multiple layers of semiconductor material.

These layers form quantum energy wells that confine electrons to particular energy states. Driven by the voltage applied across the device, the electrons traverse from one quantum well to another, and while passing through what is called an “active region” in doing so, they emit photons.

A quantum cascade laser may have as many as 75 active regions, and each electron generates a photon each time it traverses the layered structure.

Quantum cascade lasers are most commonly made of layers of InGaAs and InAlAs on an InP substrate. The laser’s wavelength range is very large, typically 3-120 micron (from IR to THz region). 

Why quantum cascade laser is better than CO2 laser for selective laser sintering?

To enhance the performance of CO2 lasers in 3D printing, quantum cascade lasers (QCLs) can be used. The wavelength of the quantum cascade laser is determined by its layers and can be tailored in a way that is impossible to do with a CO2 laser.

While CO2 laser output wavelength is limited to 2.5 μm, QCLs operate at much longer wavelengths. Mid-wave infrared production devices up to 11 μm are available, and some 25μm emitters have been made on an experimental basis.

Because QCL emits mid- and long-wave IR bands, it can have many possible applications like precision sensing, spectroscopy, medical, and military applications.

QCL’s wide tuning range and fast response times allows faster and more precise compact trace element detectors and gas analyzers, that’s why it can potentially replace CO2 laser.

For more details refer to this patent.

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