Er:fiber-based femtosecond frequency comb stabilized to an Yb+ single-ion optical frequency standard

An erbium fiber-based femtosecond optical frequency comb stabilized to an Yb+ single-ion optical frequency standard was created. For the first time, a combination of an extra-cavity acousto-optic frequency modulator with fiber outputs and an intracavity electro-optic phase modulator based on a KTP crystal were used to stabilize offset frequency and one of the optical components of the Er:fiber femtosecond comb. As a result a locking bandwidth of 30 kHz for the optical comb offset frequency has been obtained. It is shown that the relative instability introduced by the stabilization and measurement systems into the output radio frequencies (in addition to the instability of the reference optical signal) is no worse than 5 × 10−14 for averaging times of 1 s and 2 × 10−16 for averaging times of 400 s.

The optical frequency standard based on strontium cold atoms

The results obtained during the development of an optical frequency standard, based on cold 87Sr atoms are presented. The parameters of experimental optical schemes developed for the realization of all stages of sequential laser cooling and trapping of 87Sr atoms into an optical lattice are described. Clock transition spectroscopy was successfully performed with a spectral transition linewidth of 12 Hz. A measuring scheme based on a femtosecond optical frequency synthesizer has been developed, which makes it possible to compare the optical standard with a hydrogen maser. The created optical frequency standard was included in the primary standard GET 1-2018.

Stabilizing diode laser to 1 Hz-level Allan deviation with atomic spectroscopy for Rb four-level active optical frequency standard

We achieve a compact ultra-stable 420 nm blue diode laser system by immediately stabilizing the laser on the hyperfine transition line of Rb atom. The Allan deviation of the residual error signal reaches 1 Hz-level Allan deviation within 1 s averaging time, and the fractional frequency Allan deviation is $$1.4\times 10^{-15}/\sqrt{\tau }$$1.4×10-15/τ, which shows the best result of frequency-stabilized lasers based on the atomic spectroscopy without Pound–Drever–Hall (PDH) system. The signal-to-noise ratio of the atomic spectroscopy is evaluated to be 3,000,000 from the Allan deviation formula, which is the highest record, to the best of our knowledge. The frequency noise suppression characterization is demonstrated and the maximal noise suppression can be near 40 dB at 6 Hz. As a good candidate of pumping source, the ultra-stable 420 nm diode laser is successfully used in our Rb four-level active optical frequency standard system. The method can be easily extended to other wavelengths ultra-stable lasers with a Allan deviation of $$10^{-15}$$10-15 level retaining an atomic reference with low cost and low complexity while in the absence of an expensive and complicated PDH system.