Researchers develop ‘most stable laser in the world’
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Researchers claim to have developed a laser with unequalled frequency stability, which they say will be important for optical spectroscopy and offer an even more stable interrogation laser for optical atomic clocks.
The laser is the result of collaboration between Germany's Physikalisch Technische Bundesanstalt (PTB), the Centre for Quantum Engineering and Space Time Research (QUEST) and the American National Institute of Standards and Technology (NIST).
The team noted that the stability of modern resonator stabilised laser systems is only limited by the thermal noise of the resonators, which are traditionally made of glass
For a new resonator, the team used single crystal silicon, a low noise material. Cooled down to a temperature of 124K (-149°C), silicon is characterised by an extremely small thermal expansion, which further reduces the remaining thermal noise. To operate the resonator at this temperature, the researchers designed a low vibration cryostat.
Comparison measurements with two glass resonators allowed the scientists to demonstrate a frequency stability so far unequalled of 1 • 10-16 for the laser stabilised to the silicon resonator.
The team says that the laser reaches a linewidth of less than 40mHz and can therefore contribute to moving into a new dimension in the development of optical atomic clocks.
"For the future, there is still room to improve the optical mirrors whose thermal noise limits the achievable stability", said PTB physicist Christian Hagemann.
Therefore, in the future the researchers plan to go down to even lower temperatures and use novel highly reflecting structures to improve the frequency stability by another order of magnitude.
