Abstract: InGaN diode lasers emit green, blue and violet wavelengths depending on the ratios of Indium, Gallium and Nitrogen atoms. Lasers with a lower fraction of Indium are commonly referred to as GaN lasers. Since around 1995, low-power GaN lasers have served as milliwatt light sources in Blu-ray players. Medium-power multimode lasers, capable of up to 50 Watts output, are employed for cutting and joining plastic and polymer materials. The short wavelengths of these lasers enable high-resolution imaging and sensing, making blue and violet lasers particularly valuable in microscopy and biomedical applications. In industrial contexts, high-power blue lasers emitting at 450 nm have become crucial for manufacturing batteries used in electric cars and airplanes. Currently, infrared solid-state and fiber lasers, pumped by infrared diodes, dominate applications such as drilling, cutting, welding and soldering. However, the significantly higher absorption of blue and green wavelengths by copper and other non-ferrous battery materials enhanced production efficiency. This has spurred the development of high-power blue lasers specifically for manufacturing tasks. The 450 nm wavelength of blue lasers results in more collimated beams compared to infrared counterparts, due to reduced diffraction. Combining laser beams from hundreds of single blue diodes by simple stacking allows the creation of laser systems with continuous output powers in the multiple kilowatt range. In pulsed operation, peak powers of up to 10 kW can be achieved. The compact nature of direct electrical excitation systems further enhances the appeal of blue lasers over fiber lasers in certain applications.

Keywords: GaN, InGaN, Laser diodes, Sensing applications, Broad area lasers, Stacking, High power laser systems

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