Researchers at the University of Tsukuba have developed an innovative approach to producing laser light sources in large quantities using a simple, yet highly effective, technique involving an inkjet printer. This breakthrough, published in Advanced Materials, revolves around the ability to eject laser-emitting droplets that can be electrically controlled to switch the emission of light on and off. This novel method could pave the way for highly compact and energy-efficient laser displays, potentially revolutionizing the technology used in screens for televisions, smartphones, and computers.
Displays are a critical component of modern technology, and ongoing advancements aim to improve picture quality, color accuracy, brightness, and energy efficiency. Current display technologies, such as OLED (Organic Light Emitting Diodes) and LCD (Liquid Crystal Displays), have made significant strides in these areas, but they still face limitations. For example, OLEDs struggle with color consistency over time and can be relatively power-hungry, while LCDs may not be able to achieve the same level of brightness and color reproduction. Laser displays, however, have emerged as a promising next-generation technology that could overcome these limitations. With their superior brightness, higher color purity, and energy efficiency, laser displays are expected to surpass conventional displays in the near future.
A key challenge in developing laser displays, however, is miniaturizing the components to a size suitable for consumer devices, while maintaining high density and large-scale production capabilities. This is where the inkjet printing technique demonstrated by the researchers at the University of Tsukuba becomes significant. By ejecting droplets of a specific organic liquid, these researchers have created a new method for producing laser light. The droplets themselves are remarkably small—just 30 micrometers in diameter—and can be arranged densely over large areas, making them ideal for creating high-resolution displays.
What makes this approach so revolutionary is the ability to control the emission of laser light from each droplet individually. The researchers achieved this by applying an electric field to the droplets. Normally, when the droplets are spherical, they emit laser light. However, when an electric field is applied by positioning the droplets between electrodes, the shape of the droplet changes. The spherical droplet deforms into an ellipsoid, and this shape change causes the laser emission to cease. This ability to switch the laser light on and off using an electric field demonstrates that these droplets can function as electrically switchable “laser pixels,” a vital feature for any display technology.
This switchable property was successfully demonstrated in a 2×3 array of droplets, with each droplet capable of emitting light independently. This development is a significant step forward in the creation of compact and highly efficient laser displays. The ability to control each pixel individually allows for more precise and dynamic images on the screen. In addition, the high density of droplets that can be arranged on a small area opens up the possibility of creating much higher resolution displays compared to current technologies.
The potential applications of this technology are vast. Laser displays could offer several advantages over conventional displays, particularly in terms of brightness and color accuracy. Laser light sources can produce intense brightness without the need for backlighting, which is necessary in current LED and LCD technologies. This could lead to thinner, lighter displays that consume less power while offering superior image quality. Moreover, laser displays are not limited by the color reproduction constraints of OLEDs and LCDs, making them ideal for applications where high-quality color fidelity is crucial, such as in medical imaging, professional-grade monitors, and high-end entertainment systems.
Despite the promising results, there are still several challenges to overcome before this inkjet printing method can be scaled up for commercial applications. One of the key hurdles is improving the performance of the laser-emitting droplets and ensuring that they can operate reliably over long periods. Additionally, further optimization of the electrical configurations and droplet arrangement could lead to even higher performance and efficiency, which would be crucial for the widespread adoption of this technology in consumer electronics.
The study conducted by the University of Tsukuba represents a significant step toward realizing the potential of laser-based displays. By demonstrating the feasibility of using inkjet-printed laser-emitting droplets that can be switched on and off via an electric field, the researchers have opened the door to a new era of display technology. With further research and development, laser displays could soon become a viable alternative to current display technologies, offering consumers improved performance, better energy efficiency, and brighter, more vibrant images.
Reference: Masato Kato et al, Optically Pumped and Electrically Switchable Microlaser Array Based on Elliptic Deformation and Q‐Attenuation of Organic Droplet Oscillators, Advanced Materials (2024). DOI: 10.1002/adma.202413793