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A combination of fiber lasers and direct-diode lasers
Fiber lasers are often used in combination with direct-diode laser systems. A fiber laser contains an optical fiber that is an end- or side-pumped, while a direct-diode laser system includes a non-gain optical fiber that is simply filled with light that is produced from numerous laser beam diodes connected to the fiber.
It is possible to apply both fiber lasers and direct diode laser systems for material processing. High-power fiber laser systems include either single-mode or multimode outputs, while direct-diode lasers are always multimode because “the etendue of fiber optics for combining light from many laser beam diodes will be substantially above the single-mode limit”.
Improving brightness and laser output
Manufacturers of laser systems are constantly improving the brightness of laser products; herein, numerous material processing applications require the multimodal laser beam. Additionally, the majority, but not all, direct-diode laser systems emit laser beams in the near-infrared.
High-power output through wavelength multiplexing
The wavelength-multiplexing of the laser stacks and polarization-combining submodules allows achieving high-power laser beams. Thus, it is possible to achieve a power of 6 mm-mrad over a broad range of power levels from 100 W to beyond 1000 W.
Transmission and wavelength range
Moreover, a laser beam can then be transmitted to the workpiece in free space or through optical fibers with a core size of 100 or 200 µm. Finally, the laser technology of wavelength multiplexing enables such laser systems to produce within a wavelength range of 900 to 980 nm.
Laser modules for cutting, welding, and pumping
Material processing application also uses laser modules for the same purposes. To be more precise, basic laser modules can reach a bandwidth of less than 25 nm and an output power of 1.5 kW. The application of laser modules includes cutting and welding, as well as high-energy laser pumping.
Advantages of wavelength-multiplexed laser modules
Nevertheless, the laser technology of wavelength multiplexing increases the power levels of this platform far into the multi-kilowatt range without any variation in laser beam properties. Laser modules can include high-power fiber optic cables and laser processing heads, resulting in higher power and efficiency.
Applications in microelectronics, soldering, and heat treatment
The laser system demonstrates the ideal application in soldering microelectronic parts, where relatively tiny spot sizes varying from 0.2 to 3 mm are set over a fairly long working distance. Also, the fiber laser system offers such benefits as quite short rise- and fall-times (less than 10 µs), it keeps up a uniform power distribution across the laser beam, resulting in a perfect solution for multiple heat treatment applications.