As the price of diode lasers declines and performance develops, new markets are rapidly opening. In this article, technology consultancy IDTechEx demonstrates how advances in semiconductor laser technology have made new applications in laser material processing and industrial manufacturing possible.

The discussion in this paper is based on a recent report: Laser Diodes and Direct Diode Lasers - 2019 Edition. In this report, IDTechEx analyst Dr. Nilushi Wijeyasinghe gave a comprehensive review of diode laser technology, value chains, key players' activities, and global markets. Through case studies highlighting recent advances in materials processing, she used her research background in laser physics and semiconductor physics to explain new technology concepts in case studies. Based on extensive analysis of raw data and second-hand data, carefully consider the market drivers and constraints, and propose a 10-year market forecast and technology roadmap.

Development of laser diodes and diode bars

Technological advances have enabled lasers to enter a diverse range of markets from specialized technical instruments. Laser diodes are the most widely used laser technology and are simple semiconductor devices. Over the past 30 years, the average power of laser diodes has increased significantly, while the average price per watt has declined exponentially. As a result, laser diodes are replacing some of the existing laser and non-laser technologies, while also enabling new optical technologies. Mature applications for laser diodes include data storage, data communications, and optical pumping of solid-state lasers. In contrast, material processing and optical sensing are examples of the rapid development of market segments in which many emerging applications emerge.

The output power of a single laser diode varies from milliwatts to several watts. Power can be increased by combining a single emitter into a laser diode bar and several bars; a standard bar has a width of 1 cm. For decades, companies have been fiercely competing to increase the output power of diode bars, and have shown an exponential growth trend. Although in commercial diode bar products, the power of each diode bar is typically less than 200 watts at 1-micron wavelength, the R&D department of laser manufacturing companies has demonstrated the average of continuous wave (CW). Power exceeds 1 kW/bar. The increase in diode bar power has made new applications in the field of material processing possible, but some emerging applications require increased laser parameters such as wavelength stability and device lifetime. Therefore, power competition is no longer a top priority for companies in this market. The continued development of diode laser technology is reflected in the improvement of infrared beam quality for precision engineering and the development of new visible-light lasers for metal processing.

Continuous wave (CW) laser diode bar power development process

Based on the data collected and analyzed by IDTechEx, the development process of the laser diode bar output power at 1-micron infrared wavelength was studied, as shown in the figure above. The increase in diode bar power has facilitated the development of direct diode lasers and made new applications in material processing possible. The continued development of diode laser technology is reflected in the improvement of infrared beam quality for precision engineering and the development of new visible-light lasers for metal processing.

Power and precision emerging direct diode laser technology

These incredible advances in semiconductor laser technology have made it possible to develop direct diode lasers (DDLs), including high-power direct diode lasers (HPDDL) that produce several kilowatts of output power. DDL combines many diode bars with a beam shaping system, control circuitry, and a cooling unit. Technological advances have enabled DDL to generate more than 20 kilowatts of output power in multimode systems and output several kilowatts of power at higher beam quality than ever before. In addition to DDL, companies such as Laserline also produce diode lasers coupled to active fiber converters that produce 4 to 6 kilowatts of output power with an excellent beam quality of 4 to 6 millimeters per milliradian.

Continuous-wave (CW) high power direct diode laser power development process

Based on data collected and analyzed by IDTechEx, the development of the output power and beam quality of a 1-micron infrared high power direct diode laser (HPDDL) was investigated, as shown in the figure above. HPDDL is a rapidly evolving tool for material processing and industrial manufacturing.

Significant improvements in beam quality now allow users to focus the laser onto a small spot, indicating that DDL is a rapidly evolving tool for processing metals, plastics, and composites. In applications such as laser welding where high precision and deep penetration are required, DDL can now compete with fiber lasers. DDL can directly convert electrical energy into the laser, while fiber lasers are based on rare earth metal doped fibers, which must be optically pumped (energy input) through laser diodes or diode bars. The unit price of DDL is significantly lower than that of a fiber laser with a continuous wave output of 1 kW. According to major manufacturers interviewed by IDTechEx, the typical unit price of a 1 kW high-power direct diode laser and a 1 kW fiber laser in 2018 is $20,000 and $25,000, respectively. At output powers below kW, the price difference between DDL and fiber lasers is even greater. Besides, DDL emits wavelengths that are different from fiber lasers, which means that DDL can process materials more efficiently with matched absorption spectra.

Therefore, DDL and HPDDL are becoming major trends in global industrial manufacturing. To increase their position in the high-growth DDL/HPDDL market, some of the key participating companies are making strategic acquisitions and investing funds to expand capacity. For example, Matsushita of Japan acquired the US laser company TeraDiode to acquire the latter's expertise in HPDDL. This technology produces high-quality beams through a patented optical process. In general, the above technological advances have brought good business growth opportunities. IDTechEx predicts that by 2029, the global market for laser diodes and direct diode lasers will reach $14 billion, with the market for direct diode lasers reaching $2 billion. IDTechEx's report "Laser Diodes and Direct Diode Lasers - 2019 Edition" provides a detailed analysis of the market.

Laser diode subdivision application

Welding with high-brightness blue-diode lasers and 3D printing of copper materials

A particularly important trend is the development of blue direct diode lasers for applications such as soldering and copper 3D printing. In 2019, Laserline introduced a 1kW product. Blue lasers process metals faster and more efficiently, and these metals have poorer absorption of 1-micron infrared radiation from most industrial laser systems. In 2018, Shimadzu Corporation commercialized its BLUE IMPACT blue-impact diode laser, which produces 100 watts of power at high brightness. This product was developed by Shimadzu Corporation and Osaka University of Japan and is part of the national project in Japan. The BLUE IMPACT laser incorporates many of Nichia's GaN blue laser diodes, which have doubled efficiency since 2006 and an order of magnitude improvement in output power. A key application of the Shimadzu 450nm blue diode laser is 3D printing of copper materials. Copper has a high absorption rate for blue lasers, and a reduction in back reflections can make the process faster, which is a serious challenge for conventional infrared lasers. The newly developed 3D printer can print objects efficiently with pure copper powder. The existing 3D printer technology generally uses a copper alloy such as CuCr1Zr instead of pure copper.

According to the CAD model (right), use a Shimadzu BLUE IMPACT diode laser to print a pure copper object (left)

IDTechEx expects that with the commercialization of more products, Blu-ray DDL will soon be used in copper processing from 2019. IDTechEx's report "Laser Diodes and Direct Diode Lasers - 2019 Edition" is further discussed on this topic. The report assesses the advantages and challenges of adopting laser technology and provides a balanced market opportunity outlook