Blue-violet semiconductor lasers are used to read digital signals from Blu-ray discs, and the commercial development of Blu-ray products that have enabled millions of consumers to enjoy true HD in their homes would not have been possible without this core component device. Thanks to determined efforts by its engineers racing against time, Sony was able to complete development of the laser within a very tight schedule in time to start the mass-production of millions of PLAYSTATION 3 consoles, the first product to incorporate Blu-ray technology. In this interview with Masao Ikeda of Sony Advanced Materials Labratories, we learn about the numerous failures with deadlines looming in the development of the first 3 in 1 laser (CD, DVD, and BD) for the Playstation 3, and how Masao thought it would never happen.
Masao: During my time with Sony, I have been involved in the development of semiconductor lasers for optical discs, including CD, DVD and BD systems. For me the most exciting achievement, and one that required enormous effort, was the development of the blue-violet semiconductor laser.
A semiconductor laser is to an optical disc what a needle is to an analog record. The surface of an optical disc is covered with minute pits (concave areas) and ridges (convex areas). By bouncing laser beams off these areas and reading information contained in the reflected light, we can play back the content recorded on the disc. If we reduce the wavelength of the laser beam, the spot diameter of the laser is also reduced, allowing us to use smaller pits and ridges on the disc. By recording data using a laser with a short wavelength, we can store more information within the same disc area. The development of semiconductor lasers with progressively shorter wavelengths has driven the evolution of optical discs, from CDs to DVDs, and now to BDs. The laser used when playing a music CD has a wavelength of 780nm (nm=nanometer), while a DVD requires a 650nm red laser. Because the red laser used to write DVDs has a shorter wavelength, the capacity of DVDs is correspondingly greater. To create the BD, which has around five times more recording capacity than a DVD, we needed to develop a blue-violet laser capable of producing light with an even shorter wavelength.
Masao: The development of blue lasers began in the 1980s. Despite the efforts of engineers in many countries, the development of suitable materials was a slow process. Semiconductor lasers emit light when an electrical current is passed through the semiconductor used. To discover suitable materials for semiconductor lasers, we need to find combinations of substances that will produce laser light with the desired wavelength when current passes through them.
Initially Sony tried to develop a semiconductor laser using materials based on zinc selenide, and in 1996 we succeeded in maintaining continuous oscillation for 100 hours. However, Sony changed its development strategy after Nichia Corporation succeeded in developing a gallium nitride semiconductor laser with a shorter wavelength. It was a difficult decision to abandon development of the materials that we had previously been researching. However, we wanted Sony to maintain its leading role in the advancement of optical disc technology, and we saw this as the best decision in terms of ensuring that Sony would be the first to develop next-generation products based on BD technology.
Yet at this stage, we had simply selected the material that we would use. There were still many challenges to overcome before we could turn this into a semiconductor laser that could be used in commercial products. The first of these was the solution of problems surrounding Nichia Corporation’s patents relating to gallium nitride. In the second half of the 1990s, there was a patent lawsuit between Nichia Corporation and Toyoda Gosei Co., Ltd. concerning a blue LED made using gallium nitride. There was extensive media coverage about the blue LED that couldn’t be marketed because of the patent dispute. Urgent steps were needed to resolve this problem so that Sony could introduce its blue-violet semiconductor laser. However, Nichia Corporation took the position that it would sell products but not the technology, and that it would opt for licensing if there were complementing technologies. Fortunately, Sony had laser manufacturing patents, expertise and commercialization experience dating back to the CD era. We also had manufacturing facilities with world-class technology, including Sony Shiroishi Semiconductor Inc. (Sony Shiroishi), the Sony’s Group’s semiconductor laser manufacturer.
Masao: We negotiated persistently with Nichia Corporation for four-and-a-half years, with strong backing from the Patent Department and other units. This hard work eventually paid off, and we reached the conclusion that the quickest way to bring commercial products to market was to link Sony’s semiconductor laser manufacturing technology with Nichia Corporation’s basic patents for gallium nitride. In late 2002, the two companies began to collaborate on the development of a blue-violet semiconductor laser for use in optical disc applications. In April 2004, we signed a cross-licensing agreement relating to patents for a blue-violet semiconductor laser.
I was absolutely determined to develop a semiconductor laser for use in BD products. We had an unbroken history of involvement in the optical disc business. That heritage began with basic research carried out in the 1960s by a previous generation of Sony engineers and continued through to the commercialization of the CD products in the 1980s, and then to the DVD era. I could not allow that history to end, and I had to keep working until we ultimately achieved success. Both the product engineers and the device (parts) engineers were also determined to ensure that Sony would lead the development of a next-generation optical disc to succeed the DVD.
My commitment to the development project became even stronger because of the presence of another standard that was competing with Blu-ray for dominance in the next-generation optical disc market. Our determination to popularize BD technology as quickly as possible drove us to overcome the many obstacles that lay in our path.
Masao: The biggest challenge during the development project was the decision to incorporate BD capabilities into PLAYSTATION 3. The Sony Group had helped to expand the DVD market by building a DVD player into PlayStation 2. When PlayStation 2 went on sale, the DVD market was still small. The availability of a game console that could be used to play popular games and watch DVDs made DVD technology familiar to people throughout the world. Semiconductor laser technology also played a key role in the addition of CD/DVD playback capabilities to PlayStation 2. In PlayStation 2, we used a dual-wavelength semiconductor laser capable of emitting two types of lasers for CDs and DVDs. The result was a compact console that could playback both CDs and DVDs. Without doubt, the inclusion of BD playback capabilities in PLAYSTATION 3 would help popularize BD technology. However, DVD products had already been on the market for some time when PlayStation 2 was developed, and we had a little more time to develop the semiconductor laser.
The situation with PLAYSTATION 3 was totally different. When the product was under development, we only had a BD recorder capable of writing to BDs. The semiconductor laser in a BD recorder requires powerful output and is designed differently from the laser used in a player. Furthermore, we had to develop a 3-wavelength semiconductor laser capable of playing three types of optical discs–CDs, DVDs, and BDs. And because people everywhere were eagerly awaiting the launch of PLAYSTATION 3, we also needed to prepare for mass-production on a far bigger scale than for existing BD recorders. Production of the new console would be measured in millions.
Masao: In addition to developing a new semiconductor laser, we also had to design and develop equipment to mass-produce it. When I first heard about the development schedule, I thought it would be impossible. There are always problems with research and development relating to materials and devices. The conditions may be wrong, or a device fails to work properly. Progress is achieved through repeated efforts to overcome these setbacks. However, I began to think that Sony could probably succeed. I based that view on Sony’s culture of accepting difficult challenges, on the wide-ranging talents of our engineers, and on the resources of technology and experience built by our predecessors.
To take the lead in the establishment of a new optical disc format, Sony needed to succeed in mass-producing PLAYSTATION 3. The successful introduction of PLAYSTATION 3 would result in the rapid establishment of a BD market and was therefore extremely important not only to Sony, but to the entire Blu-ray industry.
Normally technology is transferred from research facilities to the Business Groups that design new products, and from there to manufacturing facilities. To minimize the time required for development, I decided to skip the transfer of technology to the Business Groups by relocating our development operations to Sony Shiroishi. I moved to Shiroishi with an elite task force of seven of our younger research workers.
Semiconductor lasers are manufactured using the metal organic chemical vapor deposition (MOCVD) method. Substrates made from gallium nitride are placed in a special kiln, in which the vaporized substances are deposited in layers to create the semiconductors. Although MOCVD is the normal method used to fabricate semiconductor lasers, this was the first time that anyone had attempted to mass-produce semiconductor lasers using materials that emit blue-violet light. Initially we experienced one failure after another. We had to identify the many conditions required to form semiconductor crystals, including precise temperature control and heating times. Each failure resulted in a delay of several weeks before we could procure new parts. The development team was close to the limit of its ability to cope with the resulting panic and pressure. Staff from Sony Shiroishi helped us by carrying out the scientific tests needed to identify the causes of key phenomena and problems. They also struggled to set up to production and testing lines in readiness for the start of mass-production. We were all locked in a relentless struggle to develop the world’s first semiconductor laser for use in a BD player. To make our task even more difficult, the laser had to be capable of emitting three different wavelengths.
As the deadline loomed ever closer, the development team was supported by the efforts of Sony engineers. The Shiroishi facility was soon crowded with semiconductor fabrication experts from Sony Semiconductor Kyushu, and research personnel working in various fields at Sony research centers. As a result of this experience, I formed a profound awareness of the bonds that exist among Sony engineers.
Engineers who choose to continue their research at universities never enjoy the satisfaction of linking research results to business through the creation of products that bring pleasure to ordinary consumers. I have experienced that satisfaction because of my involvement in Sony’s optical disc business. Once we were on track to the start of mass-production, we left Shiroishi and returned to Sony headquarters. I wanted to escape, in part because our development work had fallen behind schedule. However, when I got back to headquarters, I was greeted with applause, and everyone congratulated me for my hard work. It was in that moment that I realized how fortunate I was to have been involved in this project, and to work for Sony. The development of the BD semiconductor laser was a difficult project. I feel strongly that our success not only helped to improve our technology and knowledge, but also resulted in stronger human relationships. Perhaps it is this emotional dimension that motivates engineers to accept new challenges, regardless of the hard work required.
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