With blue lasers, brightness is the key"

As a supplier of high-power blue lasers, NUBURU Inc. from Denver, Colorado, has made a name for itself worldwide within a very short time. Co-Founder Jean-Michel Pelaprat is Chief Marketing & Sales Officer in the four-person executive board, which consists of experienced photonics specialists. In our interview, he talks about key application areas, market perspectives and the further technical development potential of blue lasers—as well as about the advantages of chip-based laser systems, which combine single diodes, over bar-based lasers. In addition, he gives an outlook on the market potential for lasers in the field of e-mobility.

Mr. Pelaprat, would you please briefly introduce NUBURU Inc. to us?

Jean-Michel Pelaprat: We are a four years old company, founded by two veterans of the lasers industry. First, it was Mark Zediker and myself. Dr. Jean-Phillip Feve and Denis Brisson, both experienced photonics specialists, completed our executive management team. NUBURU already employs a few dozen people. NUBURU´s focus lies on developing and manufacturing high power blue lasers, based on Gallium-Nitride (GaN). We are pioneers in this field. Since 2013, we developed a portfolio of more than ten patents; several dozens more are in process. We launched our first chip-based 150-Watts-(W)-Laser in 2017...

…which was promptly nominee for the Prism Award. Two years later, you offer a 500 W- and 1-kW-Laser. Is the output still scalable?

Pelaprat: We already received five awards in our short history. Also at LASER World of PHOTONICS in Munich, we were finalists of the Innovation Award. Recently Frost & Sullivan recognized us with the 2019 North American Technology Innovation Award, calling our blue laser approach “game-changing for welding metals”. To answer your question: Our lasers are by design scalable to very high power—even several tens of kilowatts. We will launch a 1.5 kW-System very soon and our current roadmap aims to 5 kW.

What are the most important applications for blue lasers with wavelengths around 445 nm?

Pelaprat: Our key market is material processing: Welding, cutting, cladding or additive manufacturing (3D Printing). Some customer projects revolve around non-metals, which we`d never thought of, while developing our technology. However, to date the key applications are in the field of metals. Non-ferrous metals like copper and gold absorb blue wavelengths to much higher degrees than infrared or green. Compered to infrared, gold absorbs 66 times more of the blue light, copper 13 times and aluminium three times. Also with nickel, stainless steel or titanium absorption is 30 to 80 percent higher. This leads to significantly increased processing speeds, efficiency and due to minimized reflection, it leads to spatter-free processes as well as defect-free material connections with higher mechanical resistance, long-term stability and increased safety. Furthermore, blue lasers lead to previously unattainable quality in copper-on-copper processing as well as in welding or cladding of dissimilar metals.

Have your lasers already entered the industrial production?

Pelaprat: Since we are a four-year-old start-up-company, we are in an early stage. We`ve delivered a fair number of lasers, that have already been qualified by our customers for several applications. However, in some segments such as the automotive industry, it often takes several years to qualify new processes. Currently we are in the application stage. Manufacturers are curious. They test our lasers and make sure of their advantages. If we pass the gates, next steps will be the engineering-, production- and finally the mass-production-stage. In some industries we`ve already reached final manufacturing qualifications. Generally, consumer electronics is faster than the automotive sector, and China does not have as many hurdles as Japan or the EU or the US. However, NUBURU is ready to enter the stage.

What are the key advantages over green or infrared laser systems?

Pelaprat: Concerning infrared the answer is easy: We solve current problems, which occur in welding-processes of high reflective metals—spatter, defects or low efficiency due to low energy-absorption. When it comes to thin foils or dissimilar metals, it is often impossible to weld with infrared wavelengths. Here our blue lasers are game changing. They dramatically improve performance and process windows. They substantially minimize heat impacts on weld surroundings such as sensitive coatings or materials decreases significantly with blue wavelengths. Compared to green lasers, key advantages are higher absorption, the already mentioned potentials to scale the output-power as well as reduced system complexity. Green lasers are infrared-lasers combined with a second harmonic crystal as converter. This technology seems mature after 30 years in the market. The systems are complex, and due to all the different stages from diode to combiner onward to a disk laser cavity and to the second harmonic, just less than 20 percent of the energy finds its way into the fiber. On the opposite, blue lasers are simple: GaN-Diodes turn electrons into photons, which they directly deliver to a combiner and onwards to the fiber. The efficiency is around 30 percent today and we are confident to increase it to up at least 50 percent over time. In regards of energy consumption, blue lasers are a greener approach than green lasers.

Why does NUBURU rely on chip-based lasers, which combine single diodes instead of perhaps simpler bar-based system setups?

Pelaprat: The chip-based technology is unique, for it combines high power and very high brightness. This enables power densities on the work piece that are several times higher than with comparable bar-based systems, which in the end of the day leads to substantially increased speed and quality in materials processing. We have consciously opted for the chip-based approach because it allows us to control the beam-direction of every single chip with its own lens. The key advantage of our approach is brightness. Because brightness is key for welding. Our lasers deliver twice the power density of comparable products in the market—30 mm/mrad instead of 60 mm/mrad for example. With our new 1.5 kW product-line we will further increase this value to 11 mm/mrad. So within one product-generation we are improving the power by factor 3 (500 W to 1.500 W) while also increasing the brightness and spot-size from 30 to 11 mm/mrad, which is almost factor 3. These numbers illustrate the potential of this young technology. In effect, we will be able to deliver power-levels of around 10 Megawatts/cm². This offers another key advantage: We can use the blue lasers with scanning systems with spot sizes of around 400 µm. Many of our customers in battery production, power electronics or Additive Manufacturing are desperately waiting for a solution like that.

E-Mobility opens up new opportunities for the laser industry. How do you assess the market and development dynamics?

Pelaprat: The world is pushing for electrification and for a shift from fossil fuels to green regenerative energies. Electric cars, scooters, bikes or even busses and trucks are on the rise worldwide. In fact, the electrification is more general and leads to an enormous demand of batteries; think of computers, smartphones, power-tools, energy storage and so on. Manufacturers are urgently seeking for solutions to increase the power density of batteries and for the processing of electric machines, power electronics and so on. Lasers are part of the solution. For example, in welding of copper and aluminium. When it comes to batteries, our welding-solutions with blue wavelengths provide better long-term stability as well as an approach to increased energy density. So far, the industry has been working with copper foils of 12 µm for the electrodes. Due to the superior precision in processing the foils with blue lasers, it will be possible to reduce the foil thickness to 6 µm, to apply more active material and thus increase the energy density significantly. In some cell phones, manufacturers have more than 200 welds of copper and dissimilar metals. They are also seeking for improved efficiency and quality. Lasers are key. They are offering a tremendous value to all those industries; and their decision-makers no longer need to be convinced of the potential of laser technology, in contrast to 20 years ago.

According to your observations, are there major differences in the transformation to E-mobility between the USA, Asia and Europe?

Pelaprat: The demand for innovative solutions is very strong in any region—especially when it comes to the processing of copper. In China, the political will to succeed in e-mobility is very high. Also in the EU, we see many programs to push green mobility forwards. The market is in an early phase, but it is already developing tremendously. We have the feeling to offer the right solutions at the right time.