Polycrystalline YAG: Insights and Answers
Your Questions Answered: Interview with an Expert on CoorsTek Polycrystalline YAG
CoorsTek Polycrystalline YAG materials provide scalable, high-performance solutions for industries such as laser technology, autonomous vehicles, and advanced medical devices. In this Q&A with CoorsTek Technical Fellow and materials science expert Martin Blees, we explore the unique properties, production challenges, and diverse applications of these advanced ceramics, highlighting how they address complex industry needs and enable groundbreaking innovations.
Polycrystalline YAG is a very unique material. Why did CoorsTek begin developing this?
CoorsTek started development of our unique Polycrystalline YAG material in response to a customer’s need for a scalable, high-volume YAG source for laser applications. The current manufacturing process for transparent materials like this is time consuming and expensive, making it prohibitive to scale.
How did CoorsTek build expertise in Polycrystalline YAG materials?
CoorsTek built our expertise in these materials through a strong background in high-purity translucent alumina production, evaluating scientific literature, and laboratory testing. Our Research and Development team here in Uden, the Netherlands has extensive experience in ceramic processing and expertise in solving difficult materials challenges.
Why are transparent ceramics so interesting?
Transparent ceramics have very unique material properties. They exhibit a much higher thermal conductivity, thermal stability, strength and hardness than other transparent materials such as glass or some polymers. Unlike monocrystalline materials, they are scalable to high volumes. Also, CoorsTek has the capability to combine multiple doping levels within a single part, unlike single crystal materials, which greatly limits their capabilities and applications.
How do CoorsTek polycrystalline materials differ from single crystal materials?
CoorsTek Polycrystalline materials differ from single crystal materials because they are much more amenable to mass fabrication. They are optically isotropic, consisting of micrometer size, randomly oriented crystals, and can be produced to near-net shape.
On the other hand, single crystal materials need several weeks to grow to a rough ‘boule', and require extensive machining to obtain the desired geometries.
What is the process for making transparent ceramics?
Making a ceramic transparent is a complex process, but the basic process is to minimize any pores or secondary crystallites, as even parts-per-million (ppm) levels of these can disrupt transparency. Achieving transparency involves careful optimization of each production step to prevent impurities from forming and to eliminate pores.
Aside from changing the color of CoorsTek polycrystalline YAG ceramics, what roles do the different dopants play?
Dopants serve various roles beyond altering material color. These dopants can be used to absorb light. The absorbed light is mostly converted into light emitted at different wavelengths, such as solid-state lasers, phosphors, and scintillators.
In some cases, absorption is used for switching in solid-state lasers, where specific wavelengths of light are absorbed to enhance performance—a process known as "Q-switching" which leverages quantum mechanical principles to convert a (quasi)-continuous input signal into short, high-energy pulses in a very compact and stable form factor without requiring expensive bulky active electrical components. Passive Q-switch lasers are currently being used to design ultramodern LiDAR systems being used in Advanced Driver Assistance Systems (ADAS) and autonomous vehicle technologies.
What types of companies / technologies are benefiting from CoorsTek doped transparent materials?
Companies that are interested in and could benefit from CoorsTek doped transparent materials include OEMs interested in laser systems, semiconductor, and medical equipment manufacturers and the aforementioned companies developing LiDAR systems for autonomous vehicle applications.
What are other applications for these Polycrystalline YAG ceramics beyond LiDAR for ADAS / autonomous vehicle applications?
Polycrystalline YAG ceramics have applications beyond LiDAR for ADAS/autonomous vehicles, including any applications requiring durability and clarity, such as solid-state lasers, medical devices (3D scanners, endoscopes), and detectors for gamma rays or high-energy particles. They can also be used as high-temperature, chemical-resistant windows in specialized equipment, optical lenses, and Faraday isolators. We also see potential for these ceramics to be used for scratch-resistant windows for personal electronics and high-end watches.
Are there similar products available (such as other polycrystalline materials that can be used in similar applications)? If so, what makes CoorsTek polycrystalline YAG ceramics superior?
Similar polycrystalline materials are available for comparable applications, but CoorsTek Polycrystalline YAG materials stand out due to their superior performance in key areas: CoorsTek ceramics offer exceptional wear and chemical resistance, high electrical resistivity at elevated temperatures, excellent thermal conductivity, and an outstanding stiffness-to-weight ratio. Additionally, CoorsTek provides both fully transparent and optically translucent ceramics, allowing tailored solutions for specific application needs. This combination of properties and versatility gives CoorsTek a competitive edge in the market.
What are the challenges in developing these materials?
Developing polycrystalline YAG ceramic materials presents significant challenges, primarily the need to eliminate pores and secondary crystallites that can compromise performance. Achieving the elimination of pores requires the use of ultra-high-purity raw materials and precise optimization of every production step. Rigorous process controls are essential to preventing defects at each stage to ensure the desired optical and mechanical properties.
Has the development of these materials led to any other product/capability developments for other applications at CoorsTek? Have these developments led to other innovations?
Yes, the development of these materials has driven innovations that extend beyond their primary applications. Specialized processes and optimizations created for these ceramics have been adapted to enhance the production and performance of other ceramic materials, enabling new capabilities and applications across various industries.
Where can we see CoorsTek Polycrystalline YAG materials?
CoorsTek materials will be on display at the Laser World of Photonics fair, taking place in Munich, Germany, in June 2025. We’ll be showcasing our latest innovations and materials at our booth (Booth B1.145) and our materials experts will be on hand to answer questions.
Biography of Martin Blees
Dr. Martin Blees is a Technical Fellow at the CoorsTek Uden Research and Development facility in Uden, the Netherlands, where he directs the development of transparent ceramic materials. He worked on soot-sensor development where he focused on electrical insulation and gastight electrical insulation and gastight electrical feedthroughs for operation in high temperature, corrosive environments.
Preceding the CoorsTek acquisition of Philips Lighting in 2018, Blees led numerous development and industrialization projects for the company, including the development and industrialization of a combined debinding and sintering process for high-volume alumina production applications, and the industrialization of co-sintered translucent alumina with metals for high-intensity discharge lamps.
Prior to this, he specialized in the development of polymeric electronic devices using advanced techniques such as monolayer patterning through microcontact printing for Philips Research.
Blees holds a Ph.D. in Physical Chemistry from Leiden University. His doctoral thesis focused on self-diffusion in polymer colloids studied by pulsed magnetic field gradient NMR.