Development of Ultra-Stable Microwave... Exploring Black Holes with Radio Telescopes

KAIST Develops Ultra-Stable Microwave Generation Technology the Size of a Mobile Phone
Applicable to Ultra-High-Speed Networks, Radar, Astronomical Observation, and Quantum Sensors

[Asia Economy Reporter Kim Bong-su] Domestic researchers have developed an ultra-stable microwave generation technology with high frequency stability. It is attracting attention as it can be used in various fields such as 5G, 6G communications, astronomical observation, radar, and portable quantum sensors.

The Korea Advanced Institute of Science and Technology (KAIST) announced on the 26th that a joint research team led by Professor Jungwon Kim of the Department of Mechanical Engineering and Professor Hanseok Lee of the Department of Physics developed a technology that generates ultra-stable microwaves with a frequency stability level of one part in two trillion (5×10^-13) from a palm-sized small device using optical chips and optical fibers.

Using this new technology, microwaves with phase noise and frequency stability far superior to existing microwave generation technologies can be generated from a small device the size of a cellphone. In the future, it will enable revolutionary performance improvements in various fields such as 5G and 6G communications, astronomical observation using radio telescopes, military radar, portable quantum sensors, and ultra-high-speed signal analysis technologies.

Recently, micro-comb technology that generates optical pulses using ultra-small microresonators has rapidly advanced. Micro-combs can increase the pulse emission rate from tens of gigahertz (GHz, one billion oscillations per second) to terahertz (THz, one trillion oscillations per second). This makes it easy to generate high-frequency microwaves or millimeter waves and miniaturize systems, playing a key role in improving bandwidth and performance of various information and communication technology systems.

Although micro-combs theoretically have pulse-to-pulse timing errors at the femtosecond (10^-15 seconds = one quadrillionth of a second) level, their performance is easily affected by the surrounding environment due to the characteristics of small devices, making it difficult to maintain performance over long periods. To solve this, micro-combs can be frequency-locked to mechanically stable devices to improve stability, but until now, such stabilization devices have been very complex, sensitive to vibration, and bulky, which prevented leveraging the advantages of ultra-small micro-combs and limited their application outside laboratories.

The research team developed a technology to stabilize the frequency of micro-combs using optical fibers to solve this problem. A 1 km long optical fiber has a theoretical length stability limited by thermomechanical noise at the level of one part in a thousand trillion, which is excellent, while being compact, very lightweight, and inexpensive. The team was able to implement this fiber-based stabilization device in a size of 108 mm × 73 mm × 54 mm.

As a result, the timing error of the generated 22-gigahertz (GHz) microwave was reduced to the 10-femtosecond level, more than six times better than commercial high-performance signal generators, and the frequency stability was improved to the level of one part in two trillion (5×10^-13).

This technology can simultaneously generate microwaves and optical pulses with very low phase noise and high frequency stability, making it applicable in various cutting-edge scientific and technological fields. For example, in very long baseline interferometers based on radio telescopes, using microwaves and optical pulses with higher frequencies and lower noise can dramatically improve measurement resolution and observation precision, enabling exploration of new astronomical phenomena such as the event horizon of black holes that were previously unobservable.

Professor Kim explained, "We are conducting follow-up research to apply the newly developed ultra-stable technology to various fields such as communications, radar, data converters, and radio telescopes," adding, "We are also working on improving the optical characteristics of microresonators, the core components implemented on silicon chips, to further enhance performance."

The research results were published on the 19th in the international academic journal Nature Communications.

This content was produced with the assistance of AI translation services.