The groundbreaking sound laser, developed by Hui Jing and his team at Hunan Normal University, boasts several remarkable features that set it apart from previous iterations. At its core is a one-micrometre-long silica bead, roughly the size of a typical bacterium, surrounded by a reflective cavity12. This innovative design allows for a tenfold increase in brightness compared to earlier phonon lasers, significantly amplifying the power delivered at each phonon frequency2. Unlike its predecessors, which operated for only a few minutes, this upgraded version can function continuously for over an hour, showcasing exceptional durability and efficiency32. The addition of an electrode beneath the bead further enhances the laser's performance, producing carefully selected electromagnetic signals that contribute to its increased power and precision2.

The operational mechanism of China's groundbreaking sound laser represents a sophisticated blend of optical and mechanical principles. Here's a concise overview of how this powerful phonon laser functions:

• Two light beams levitate a silica microbead (about 1 micrometer long) within a reflective cavity12

• The bead's vibrations generate phonons, which are trapped and amplified in the cavity2

• An electrode beneath the bead produces electromagnetic signals, enhancing the laser's performance12

• This setup creates a laser-like beam of sound particles (phonons) that is:

  • 10 times more powerful than previous phonon lasers1

  • Capable of operating continuously for over an hour32

  • More focused and stable due to the "locking" of sound waves4

• The device emits sound in the terahertz frequency range, opening up possibilities for various applications3

This innovative design overcomes previous limitations in phonon laser technology, significantly improving both power output and operational duration12.

The phonon laser's unique properties open up a wide range of potential applications across various fields. In medical imaging, its ability to penetrate watery tissues more effectively than light-based lasers could lead to more precise and less invasive diagnostic techniques1. The technology shows promise for deep-sea exploration, potentially enhancing communication and navigation systems for underwater vehicles2. Additionally, the sound laser's capacity to emit in the terahertz frequency range could revolutionize security measures, such as improving airport scanning procedures3. Other potential applications include:

• Optoelectronics and signal modulation

• Nanoparticle manipulation

• Atmospheric monitoring

• Acoustic frequency comb generation

• Ultrasound sensing

• Biomedical diagnosis of levitated micro-size objects4

This development marks a significant milestone in laser innovation, known as Sound Amplification by Stimulated Emission of Radiation (SASER)1. By overcoming previous limitations in phonon laser technology, it paves the way for practical applications that were once out of reach. The enhanced power, precision, and durability of this new sound laser represent a leap forward in the field, potentially revolutionizing areas such as quantum computing and material science2.

While still in its early stages, this breakthrough has generated excitement comparable to the impact of optical lasers on modern life3. However, experts like Richard Norte from Delft University of Technology caution that years of research and engineering may be required before phonon lasers can match the usefulness of their optical counterparts3. Nonetheless, the potential for transformative applications across various scientific and technological domains remains promising.