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The principle of laser enhanced welding is based on the interaction between the electrical arc and laser radiation. Due to the optogalvanic effect (OGE) a channel of higher conductivity in the plasma is established along the path of the laser. [1] Therefore, a movement of the laser beam results in a movement of the electrical arc.
With laser diodes where narrow linewidth is required, direct modulation is avoided due to a high bandwidth "chirping" effect when applying and removing the current to the laser. Optical modulators are used with superconductors which work properly only at low temperatures, generally just above absolute zero .
Laser beam welding (LBW) is a welding technique used to join pieces of metal or thermoplastics through the use of a laser. The beam provides a concentrated heat source, allowing for narrow, deep welds and high welding rates.
Schematic diagram of a typical laser, showing the three major parts. A laser is constructed from three principal parts: An energy source (usually referred to as the pump or pump source), A gain medium or laser medium, and; Two or more mirrors that form an optical resonator.
Laser types with distinct laser lines are shown above the wavelength bar, while below are shown lasers that can emit in a wavelength range. The height of the lines and bars gives an indication of the maximal power/pulse energy commercially available, while the color codifies the type of laser material (see the figure description for details).
Diagram of a simple VCSEL structure. The vertical-cavity surface-emitting laser (VCSEL / ˈ v ɪ k s əl /) is a type of semiconductor laser diode with laser beam emission perpendicular from the top surface, contrary to conventional edge-emitting semiconductor lasers (also called in-plane lasers) which emit from surfaces formed by cleaving the individual chip out of a wafer.
The input laser light (bottom of the picture, not visible before entry into the fiber) is near-infrared and generates wavelengths covering most of the visible spectrum. Supercontinuum generation from a photonic crystal optical fiber (seen as a glowing thread on the left) for gradually increasing intensity of a pump laser.
The active laser medium (also called a gain medium or lasing medium) is the source of optical gain within a laser. The gain results from the stimulated emission of photons through electronic or molecular transitions to a lower energy state from a higher energy state previously populated by a pump source .