From The Tokyo Institute of Technology [東京工業大学] (JP)
4.8.24
Further Information
Associate Professor Kentaro Somiya
School of Science, Tokyo Institute of Technology
Email somiya@phys.titech.ac.jp
Specially Appointed Assistant Professor Sotatsu Otabe
Institute of Innovative Research,
Tokyo Institute of Technology
Email otabe@qnav.iir.titech.ac.jp
Contact
Public Relations Division, Tokyo Institute of Technology
Email media@jim.titech.ac.jp
Tel +81-3-5734-2975
A novel technique for enhancing optical spring that utilizes the Kerr effect to improve the sensitivity of gravitational wave detectors (GWDs) has recently been developed by scientists at Tokyo Tech. This innovative design uses optical non-linear effects from the Kerr effect in the Fabry-Perot cavity to achieve high signal amplification ratios and optical spring constant, with potential applications in not only GWDs but also in a range of optomechanical systems.
The detection of gravitational waves stands as one of the most significant achievements in modern physics. In 2017, gravitational waves from the merger of a binary neutron star were detected for the first time which uncovered crucial information about our universe, from the origin of short gamma-ray bursts to the formation of heavy elements. However, detecting gravitational waves emerging from post-merger remnants has remained elusive due to their frequency range lying outside the range of modern gravitational wave detectors (GWDs). These elusive waves hold important insights into the internal structure of neutron stars, and since these waves can be observed once every few decades by modern GWDs, there is an urgent need for next-generation GWDs.
One way to enhance the sensitivity of GWDs is signal amplification using an optical spring. Optical springs, unlike their mechanical counterparts, leverage radiation pressure force from light to mimic spring-like behaviour. The stiffness of optical springs, such as in GWDs, is determined by the light power within the optical cavity. Thus, enhancing the resonant frequency of optical springs requires increasing the intracavity light power which, however, can result in thermally harmful effects and prevent the detector from working properly.
To address this issue, a team of researchers from Japan, led by Associate Professor Kentaro Somiya and Dr. Sotatsu Otabe from the Department of Physics at Tokyo Tech, developed a groundbreaking solution: the Kerr-enhanced optical spring. “A promising method to enhance the impact of optical springs without increasing intracavity power is intracavity signal amplification. This technique enhances the signal amplification ratio of the cavity by using non-linear optical effects and enhances the optical spring constant. Our research revealed that the optical Kerr effect is a promising approach for successfully utilizing this technique,” explains Prof. Somiya. Their findings were published in the journal Physical Review Letters. In addition, this letter has been selected as an Editors’ Suggestion, a weekly recognition aiming to promote interdisciplinary engagement.
This groundbreaking design involves generating intracavity signal amplification effect in a Fabry-Perot type optomechanical cavity by inserting a Kerr medium. The Kerr medium induces an optical Kerr effect in the cavity, in which an optical field changes the refractive index of the medium. This introduces a drastic gradient of the radiation pressure force in the cavity, enhancing the optical spring constant without increasing intracavity power.
Experiments revealed that the optical Kerr effect successfully enhances the optical spring constant by a factor of 1.6. The resonant frequency of the optical spring was increased from 53 Hz to 67 Hz. The researchers anticipate an even larger signal amplification ratio with refinement of technical issues.
“The proposed design is easy to implement and provides a novel tuneable parameter for optomechanical systems. We believe that demonstrated technique will play a key role not only in GWDs but also in other optomechanical systems, such as in cooling macroscopic oscillators to their quantum ground state,” says Dr. Otabe, emphasizing the importance of this study.
Overall, this novel optical spring design represents a significant stride towards harnessing the full potential of optomechanical systems as well as enhanced GWDs capable of unravelling the mysteries of our universe.
Current gravitational wave detctors
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LIGO-VIRGO-KAGRA-GEO 600-LIGO-India-ESA/NASA LISA
For the future
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The Tokyo Institute of Technology [東京工業大学] (JP) is the top national university for science and technology in Japan with a history spanning more than 130 years. Of the approximately 10,000 students at the Ookayama, Suzukakedai, and Tamachi Campuses, half are in their bachelor’s degree program while the other half are in master’s and doctoral degree programs. International students number 1,200. There are 1,200 faculty and 600 administrative and technical staff members.
In the 21st century, the role of science and technology universities has become increasingly important. Tokyo Tech continues to develop global leaders in the fields of science and technology, and contributes to the betterment of society through its research, focusing on solutions to global issues. The Institute’s long-term goal is to become the world’s leading science and technology university.
Schools and departments
TokyoTech comprises 6 schools, a number of departments and Institute for Liberal Arts.
School of Science (ja)
Department of Mathematics
Department of Physics
Department of Chemistry
Department of Earth and Planetary Science
School of Engineering (ja)
Department of Mechanical Engineering
Department of Systems and Control Engineering
Department of Electrical and Electric Engineering
Department of Information and Communication Engineering
Department of Industrial Engineering and Economics
School of Life Science and Technology (ja)
Department of Life Science and Technology
School of Computing (ja)
Department of Mathematical and Computing Science
Department of Computer Science
School of Environment and Society (ja)
Department of Architecture and Building Engineering
Department of Civil and Environmental Engineering
Department of Transdisciplinary Science and Engineering
Department of Social and Human Sciences
Technology Innovation Management / Department of Innovation Science
Institute for Liberal Arts
Research laboratories
Chemical Resources Laboratory
Precision and Intelligence Laboratory
Materials and Structures Laboratory
Research Laboratory for Nuclear Reactors
Quantum Nano Electronics Research Centre
Earth-Life Science Institute (ELSI)
Centers
Politics and social sciences
Centre for Research in Advanced Financial Technology (Tokyo Institute of Technology)
Precision and Intelligence Laboratory (Tokyo Institute of Technology)
Solutions Research Laboratory
Integrated Research Institute
Global Edge Institute (Tokyo Institute of Technology)
Productive Leader Incubation Platform
Academy for Global Leadership
Centre for Research and Development of Educational Technology (Tokyo Institute of Technology)
Research Centre for Educational Facilities
Creative Research Laboratory
Research Centre for the Science of Institutional Management of Technology
Collaboration Centre for Design and Manufacturing (CODAMA)
Centre for Agent-Based Social Systems Sciences (Tokyo Institute of Technology)
Foreign Language Research and Teaching Centre
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Asia-Africa Biology Research Centre
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Career Advancement Professional School
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Centre for Liberal Arts
Engineering and computing
Materials and Structure Laboratory (Tokyo Institute of Technology)
Frontier Research Centre
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Inter-departmental organization for Informatics
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International Research Centre of Macromolecular Science
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Physics and astronomy
Volcanic Fluid Research Centre (Tokyo Institute of Technology)
Research Laboratory for Nuclear Reactors (Tokyo Institute of Technology)
Research Centre for Low Temperature Physics
Quantum Nanoelectronics Research Centre
Centre for Urban Earthquake Engineering
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Research Centre for the Evolving Earth and Planets
Centre for Research into Innovative Nuclear Energy Systems
Other facilities
Asia-Oceania Top University League on Engineering
Tokyo Tech Archive Initiative
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Tokyo Tech Front
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ICE Cube Centre
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