Macquarie Laser Breakthrough Shatters Linewidth Limits

New Raman Scattering Technique Achieves Ten Thousand-Fold Narrowing

Scientists at Macquarie University have unveiled a groundbreaking laser purification method, significantly improving spectral purity for critical scientific applications. This novel technique offers unprecedented control over laser frequency, a key factor in fields ranging from quantum computing to advanced sensing.

Raman Scattering Outperforms Brillouin Lasers

The project, detailed in APL Photonics, utilizes stimulated Raman scattering to drastically narrow a laser beam’s linewidth. This advancement surpasses current methods, such as Brillouin lasers, by a substantial margin.

“Our technique uses stimulated Raman scattering, where the laser stimulates much higher frequency vibrations in the material, and is thousands of times more effective at narrowing linewidth,” explained **Richard Mildren** of the MQ Photonics Research Centre. He contrasted this with existing Brillouin lasers, noting, “One current method to narrow laser linewidth uses Brillouin lasers, where sound waves interact with light; but the effect is relatively weak, typically narrowing by only tens to hundreds of times.”

Diamond Crystal Enhances Vibration Damping

The Macquarie team’s approach leverages the intrinsic properties of diamond crystals. These materials, chosen for their excellent thermal characteristics and stability, facilitate the efficient dissipation of laser phase fluctuations as vibrations.

In their experiments, a laser beam with a linewidth exceeding 10 MHz was directed through a small diamond crystal within a specialized cavity. The Raman scattering process effectively transferred the laser’s inherent phase noise into vibrational energy within the diamond, where it was absorbed in mere trillionths of a second.

The outcome was a dramatic reduction in the laser beam’s linewidth, narrowed to the 1 kHz limit of the detection equipment. This represents a reduction factor greater than 10,000, with potential for even greater improvement.

“Our computer modeling suggests we could narrow laser linewidth by more than 10 million times using variations of the current design,” added Macquarie’s **David Spence**. This enhanced spectral purity could revolutionize fields like atomic clocks and gravitational wave detection.

Future Applications in Quantum Technology

The breakthrough holds significant promise for quantum computing, where precise laser control is paramount. Reducing phase noise is crucial for minimizing errors in quantum computations.

Richard Mildren emphasized the broad applicability of the new method: “We are essentially proposing a new technique for purifying the spectrum of lasers that can be applied to many different types of input lasers.”

The development aligns with a growing need for high-precision optical components. For instance, the accuracy of modern GPS systems relies on atomic clocks that benefit from more stable laser frequencies, with the global market for atomic clocks projected to reach $1.7 billion by 2027 (Fortune Business Insights 2024).