Enhancing gravitational wave detectors with Kerr-enhanced Optical Springs

Enhancing gravitational wave detectors with Kerr-enhanced Optical Springs
by Riko Seibo
Tokyo, Japan (SPX) Apr 08, 2024

Since the landmark detection of gravitational waves from a binary neutron star merger in 2017, researchers have been pushing the boundaries of physics to uncover more about our universe. These waves have revealed information from the origins of gamma-ray bursts to the genesis of heavy elements. Yet, the weaker waves emitted from post-merger remnants, which could provide critical insights into neutron star interiors, remain undetected by today's standard gravitational wave detectors (GWDs) due to their low frequency range.

To address this challenge, Tokyo Institute of Technology's researchers, led by Associate Professor Kentaro Somiya and Dr. Sotatsu Otabe from the Department of Physics, have innovated a new approach to enhance the sensitivity of GWDs without compromising their operational integrity. Their solution? The Kerr-enhanced optical spring.

Optical springs utilize the radiation pressure force exerted by light to create a spring-like effect in optomechanical systems. The rigidity of these optical springs is typically governed by the power of light within the cavity. Increasing this power can undesirably raise internal temperatures and disrupt detector performance. The team's breakthrough involves amplifying the signal within the cavity through a non-linear optical effect known as the Kerr effect, which magnifies the optical spring constant effectively without additional intracavity power.

"Our method leverages the optical Kerr effect to modify the refractive index of the medium dynamically, increasing the radiation pressure's gradient and thus the spring's stiffness, all without a higher power requirement," explains Prof. Somiya. This innovative technique has yielded a significant enhancement in the optical spring constant by 1.6 times, pushing the resonant frequency from 53 Hz to 67 Hz. The results of these experiments have been well received, gaining an Editors' Suggestion from Physical Review Letters for their potential impact across various scientific fields.

The application of this technology extends beyond gravitational wave detection. According to Dr. Otabe, "This technique not only advances the field of gravitational wave astronomy but also could be helpful in other areas, such as cooling large-scale mechanical oscillators down to their quantum ground state."

As the team continues to refine their design, the broader implications for both theoretical and applied physics are immense. With further development, this Kerr-enhanced optical spring could significantly expand the capabilities of next-generation gravitational wave detectors, enabling them to detect more frequent and subtle cosmological events. The integration of such advanced technologies heralds a new era in our ability to probe the deeper mysteries of the cosmos.

Research Report:Kerr-Enhanced Optical Spring