Researchers at the University of Hyderabad have developed a novel method for transmitting data using organic crystals. The research offers a flexible, more efficient alternative to traditional glass-based fibre optics. By using an organic crystal known as salicylaldehyde azine (SAA), the researchers have created a waveguide, which provides a physical path for light to follow, that can receive and transmit signals from almost any direction. The study demonstrates a system capable of sending high-fidelity images and even encrypted messages using nothing but visible light.
Did You Know? While Wi-Fi is great, Visible Light Communication (VLC) can theoretically reach speeds 100 times faster than standard Wi-Fi! And, since light cannot pass through opaque walls, a Li-Fi network in your living room is naturally un-hackable from the street. |
The team were working on improving a technology known as Visible Light Communication, or VLC. While we currently rely on radio waves for Wi-Fi, VLC uses the visible light spectrum to carry information. This is not only faster but also more secure, as light cannot pass through walls to be intercepted by hackers. However, traditional fibre-optic communication usually relies on rigid silica fibres or semiconductors that require precise, straight-line alignment to function. If the light hits a standard fibre at the wrong angle, the signal is often lost. The researchers solved this by growing needle-shaped crystals of an organic compound called salicylaldehyde azine. These crystals are not only flexible but also active waveguides, meaning they can absorb and re-emit light at different wavelengths or in different colours, allowing them to capture signals from any angle.
To test their new system, the team built a prototype device using a microcontroller and laser diodes. They demonstrated that the crystal could operate in two distinct modes. In passive mode, it acted like a traditional optic cable, bouncing red light through its internal structure. In active mode, it absorbed violet light and re-emitted it as a bright yellow glow that travelled along the crystal. By flicking these lasers on and off at incredibly high speeds, a process called on-off keying, they were able to translate digital data into pulses of light. They successfully transmitted a grayscale image and a hidden text message reading “Hi there" embedded within a stream of data, proving the system’s potential for high-security communication.
Standard optical fibres are picky; they usually require light to enter at a specific critical angle to propagate through the core, a challenge known as the ‘alignment trap’. Because the SAA crystal is active and glows when illuminated, it can collect information from nearly any direction, making it much easier to use in real-world settings where devices might be moving. Furthermore, unlike the brittle glass used in current internet cables, these organic crystals are flexible and can be integrated into tiny, wearable electronics or flexible screens.
The research did observe a moderate decline in light intensity during the first few hours of continuous use. While the signal stabilised after this initial period and remained reliable for over 132 hours, further research is needed to ensure the materials can last for years in a commercial setting. Nevertheless, this research offers a glimpse of a future in which our light bulbs and mobile devices communicate seamlessly through a web of glowing, flexible crystal cables. By providing a platform that is both compact and highly secure, this technology could lead to ultra-fast Li-Fi in homes and hospitals, underwater communication where radio waves fail, and even wearable tech that stays connected no matter how much the user moves. It brings us one step closer to a world where data is as ubiquitous and accessible as the light in a room.
This article was written with the help of AI and edited by an editor at Research Matters.
