image: Figure | Tunable Multicolor Luminescence and Image Generation in RE3+-Doped Glasses Using Laser Excitation Modulation. a, Luminescence photographs of RE3+-doped glasses showing multicolor upconversion luminescence tuning (1–8) under varying excitation frequencies and pulse widths with 980 nm and 808 nm laser excitation. b, Synchronization of separate mirror signals via pulse modulation using two waveform generators to tailor parameters such as frequency, pulse width, and power density to optimize laser operation, and construction of selected image. c) (upper row) Front view photographs depicting the color images emitted from the RE3+-doped monolithic glasses (red circle under 980 nm continuous excitation (left), green bird under 980 nm pulsed excitation (middle), blue cat 808 nm continuous excitation (right), (lower row) Schematic illustration of the computational design process for generating images (left), side views of images (a green cube (middle) and a green cylinder (left)) created in the volume of glass sample under 980 nm pulsed excitation under standard indoor lighting conditions and in darkness, respectively.
Credit: by Utku Ekim, Diğdem Özkutay et al.
The limitations of two-dimensional (2D) displays in representing the depth of the three-dimensional (3D) world have prompted researchers to explore alternatives that offer a more immersive experience. Volumetric displays (VDs), which generate 3D images using volumetric pixels (voxels), represent a breakthrough in this pursuit. Unlike virtual reality or stereoscopic displays, VDs deliver a natural visual experience without requiring head-mounted devices or complex visual tricks. Among these, laser-based VDs stand out for their vivid colors, high contrast ratios, and wide color gamut. However, the commercial viability of such systems has been hindered by challenges such as low resolution, ghost voxels, and the absence of tunable, full-color emission in a single material.
To address these limitations, researchers from Yildiz Technical University, led by Miray Çelikbilek Ersundu, and Ali Erçin Ersundu, have developed innovative RE3+-doped monolithic glasses (RE = Ho, Tm, Nd, Yb) capable of tunable full-color emission under near-infrared (NIR) laser excitation. Their work, recently published in Light: Science & Applications, demonstrates the potential of these glasses as materials for dynamic, full-color laser-based VDs, overcoming key obstacles faced by existing technologies.
The team’s approach leverages the unique optical properties of rare-earth ions in glass matrices, which provide several advantages over crystalline materials. These glasses exhibit high optical transmittance, thermal and chemical stability, low phonon energy, and superior mechanical strength. Additionally, their ease of large-scale production and high rare-earth solubility make them ideal candidates for practical applications. By optimizing the glass composition and excitation parameters, the researchers achieved tunable red, green, and blue (RGB) emission from a single material using 808 nm and 980 nm laser excitation.
The team demonstrated the practical application of their materials by constructing a prototype VD system. Using the RE3+-doped monolithic glasses, they generated dynamic 3D images with precise control over voxel position and color. The system’s ability to achieve high spatial resolution, dynamic imagery, and full-color tunability highlights its potential for use in medicine, education, engineering, and entertainment.
"The developed glasses represent a remarkable step forward in the advancement of laser-based volumetric displays, offering a unique combination of functionality, scalability, and ease of fabrication," the researchers noted. "By overcoming the limitations of previous approaches, this breakthrough lays the groundwork for innovative 3D visualization technologies. With their exceptional versatility and efficiency, these specially designed glasses have the potential to revolutionize next-generation display systems and redefine how we interact with visual information."
"These glasses can also be utilized for a range of purposes in real-world applications," the team added. "They offer the ability to perform in-situ high-resolution 3D imaging, rapidly adjust the color and resolution of voxel images in real-time, and dynamically control the spatial arrangement of these images without the need for complex systems. Given the tunability and scalability of the materials, their use can extend beyond traditional displays into fields such as medical imaging, educational tools, and interactive entertainment, where both vivid color and precision are essential."
Article Title
Full-Color Dynamic Volumetric Displays with Tunable Upconversion Emission from RE³⁺-Doped Glasses (RE = Ho, Tm, Nd, Yb) under NIR Laser Excitation