Gaussian lasers are more common and more cost-effective than laser sources with other beam profiles. Most high-quality single-mode laser sources emit beams following a low-order Gaussian irradiance distribution (also known as TEMoo mode). Lower quality light sources will also have other laser modes to some degree, but it is often assumed that the laser beam has an ideal Gaussian distribution to simplify system modeling.
If a Gaussian beam and a flat-top beam have the same average optical power, the peak irradiance of a Gaussian beam will be twice that of a flat-top beam. When a Gaussian beam propagates through an optical system, the Gaussian irradiance distribution remains even if the peak value or beam size changes. This means that the Gaussian beam remains constant under transformation.
What's wrong with Gaussian beams?
Gaussian laser profiles have several disadvantages, such as low-intensity portions on either side of the beam's usable central area, called "wings." These wings often contain wasted energy because their strength is lower than required for a given application, including materials processing, laser surgery, and other applications that require strength greater than the strength of the wings.
For many applications, flat-top laser beam profiles utilize energy more efficiently than Gaussian beam profiles. In a Gaussian beam profile, excess energy above the intensity threshold required by the application, and energy below the threshold requirement in its outer parts or wings, are wasted.
The wings of the Gaussian beam may also damage surrounding areas beyond the target area, thereby expanding the heat-affected zone. This is very detrimental for applications such as laser surgery and precision material processing. In this case, priority is given to high accuracy and minimal damage to the surrounding area. Due to this effect, features formed using a Gaussian beam will not have particularly smooth edges, which will obviously reduce system accuracy.
