Classification of laser

Classification of laser
There are multiple ways to classify laser:
The main distinction is based on the material of the gain medium, as well as the energy form (light emission form) that interacts with the material. 1. Working medium: also known as gain medium, refers to a substance used to achieve particle number reversal and generate stimulated radiation amplification of light. The working medium determines the wavelength of the laser that can be radiated by the laser, and can be divided into solid (crystal, glass, gas (atomic gas, ionic gas, molecular gas), semiconductor, liquid and other media according to different forms.
1.1 Fiber laser
The current mainstream in the market uses ytterbium doped fiber as the gain medium with a wavelength of 1060nm, which is further divided into fiber and disc lasers according to the shape of the medium; Fiber optic represents IPG, and disc represents Fast.
1.2 Semiconductor laser
The gain medium is a semiconductor PN junction, and the wavelength of semiconductor lasers is mainly at 976nm. Currently, semiconductor near-infrared lasers are mainly used for cladding, with light spots above 400um.
1.3 Carbon dioxide laser
The gain medium of a carbon dioxide laser is helium and CO2, and the laser wavelength generated is 10.6um, which is one of the earliest laser products on the market. Early laser welding mainly used carbon dioxide lasers, which are currently mainly used for welding and cutting non-metallic materials (fabrics, plastics, wood, etc.). They are also used in lithography machines. Carbon dioxide lasers cannot be transmitted through optical fibers and have a spatial optical path. The earliest ones were done well and have been widely used in cutting equipment.
2. Classified by the form of energy action: pulsed laser (PULSE), quasi continuous laser (QCW), continuous laser (CW)
2.1 Pulse laser
Nanoseconds, picoseconds, and femtoseconds are high-frequency pulse lasers (ns or pulse width) that can often achieve high peak energy and high frequency (MHZ) processing. They are used for processing thin copper aluminum dissimilar materials, as well as cleaning. By utilizing high peak energy, they can quickly melt the base material, with low action time and small heat affected zone. They have advantages in processing ultra-thin materials (below 0.5mm)
2.2 Quasi Continuous Laser (QCW Laser)
Due to its high repetition rate and low duty cycle (below 50%), the quasi continuous fiber laser has a pulse width of 50us-50ms, filling the gap between kilowatt level continuous fiber lasers and Q-switched pulse lasers. The peak power of quasi continuous fiber lasers can reach 10 times the average power in continuous mode operation. QCW lasers generally have two modes, one is continuous welding at low power, and the other is high peak power pulse laser welding at 10 times the average power, which can be achieved. Nowadays, thicker materials and more heat are used for welding, while also being able to control the heat within a very small range
2.3 Continuous laser (CW laser)
This is the most commonly used laser, and most of the ones seen on the market are continuous lasers that continuously output laser for welding processing. Fiber lasers are further divided into single-mode and multi-mode lasers based on different core diameters and beam qualities, which can be adapted for different application scenarios.