Researchers from Imperial College London's Department of Materials have crafted a cutting-edge portable maser, shrinking the technology to fit within the confines of a compact shoebox. Imperial College London had previously pioneered room-temperature solid-state masers in 2012, a milestone that underscored their capability to amplify faint electrical signals with high-frequency stability. This innovation is particularly noteworthy as microwave signals, crucial for various applications, can traverse the Earth's atmosphere more efficiently than other light wavelengths. Notably, microwaves can penetrate the human body, a feat beyond the reach of lasers.
Masers play a pivotal role in telecommunications, spanning mobile phone networks to satellite navigation systems, and contribute significantly to the advancement of quantum computing and enhancements in medical imaging, such as MRI machines. Traditionally, masers were cumbersome, stationary behemoths confined to research laboratories. However, this new study has devised a means to render masers significantly more compact and portable. The novel device, weighing a mere few kilograms and resembling a shoebox, has the capacity to amplify microwave signals at an affordable cost. The breakthrough relies on a pentacene gain material—a chain of five benzene rings capable of “masing” at room temperature.
Dr. Wern Ng, the lead author of the published paper in Applied Physics Letters, emphasized the transformative nature of their achievement. “Masers always needed very cold temperatures, and they usually needed vacuums, which made them very heavy. We have managed to shrink the maser to only 5 kilograms, with no cooling needed, no need for a vacuum, and it is all solid-state.”
What distinguishes this portable maser is its status as the first room-temperature maser of its kind—operating close to the quantum limit yet compact and lightweight enough for portability. Dr. Ng stresses the importance of portability, stating, “Portability is key to encouraging more people to use this device. It makes all the difference when someone can hold a device and easily flick a switch.”
The journey to this groundbreaking design was not without challenges, with miniaturizing the pump source proving to be a significant hurdle. While the room-temperature gain material eliminated the need for cooling, the existing masers still required a large, high-energy pump. Dr. Daan Arroo, another author of the paper, highlighted the intricacies involved, “You have to think about what is absolutely essential when making a maser the size of a shoebox! Our biggest challenge was reducing the required pulse energy to a level low enough that a compact pulsed laser could pump the maser.”
Looking ahead, the researchers envision further miniaturization of the design. Dr. Arroo suggests, “It may be possible to replace the laser with a smaller LED-based light source if we can reduce the energy required for pumping the molecules. We are also considering how a diamond maser, which can also operate at room temperature, can be miniaturized to a portable form.”
Diamond masers, with their ability to operate continuously compared to the pulsed operation of pentacene masers, hold promise for expanded applications. Dr. Ng concludes optimistically, “We have shown that we can successfully miniaturize the pentacene maser. The pentacene maser is extremely useful; however, it cannot offer a continuous beam—unlike diamond masers. Our next task is miniaturizing room temperature masers with different gain media such as diamond.” This heralds a new era where portable masers, once confined to the realms of imagination, are poised to revolutionize diverse fields, from telecommunications to medical technology.
Source: Imperial College London – Department of Materials