Search

We report recent results on the development of an optical frequency standard based on the quadrupole transition in a single 171Yb+ ion. The probe laser frequency is simultaneously stabilised to the transmission peak of a Fabry – Perot reference cavity and the central resonance of the quadrupole transition of the ion with a linewidth of 30 Hz. With the experimentally obtained spectral characteristics of the probe laser and optical reference, a daily frequency stability on the order of 10−17 is demonstrated for the 171Yb+ standard.

We outline the results of the spectroscopic investigation of the quadrupole transition of a single ytterbium-171 ion as applied to the development of an optical frequency standard with a relative uncertainty and long-term frequency instability of less than 10−17. The spectral width of the resonance recorded at the centre transition frequency amounts to about 30 Hz.

The research analyzes observation materials and condition assessment of 100-year geographical Scots pine forest cultures created in 1913 by professor Ogievsky V D on drained lands of the Okhta forestry territory to study the intensity of Scots pine trees growth depending on the seeds origin. The planting material was grown from seeds collected in the northern, southern, eastern, southwestern and central parts of Russia. The growth of Scots pine cultures was studied and changes in wood stock, trees amount, annual increments, influence of meteorological factors on radial increments were analyzed depending on the origin of the planting material. The results of research show that sustainable and highly productive cultures can be grown from seeds of northern and eastern regions of Russia.

We have demonstrated the possibility of measuring the femtosecond laser frequency comb shift by the position of a Fabry — Perot interferometer's transmission bands with a statistical error of 10-2 and a systematic shift of 10-1.

A laser system for Doppler cooling of ytterbium ion on the {sup 2}S{sub 1/2} → {sup 2}P{sub 1/2} transition in a single-ion optical frequency standard is developed. The second harmonic of a semiconductor laser with a wavelength of 739 nm is used for cooling. The laser frequency is doubled in a nonlinear BiBO crystal embedded in a ring resonator, which also serves as a reference for laser frequency stabilisation. Second-harmonic power of ∼100 μW is generated at a wavelength of 369.5 nm. Diode laser radiation is modulated by an electro-optic modulator at 14.75 GHz to generate a sideband exciting the {sup 2}S{sub 1/2} (F = 0) → {sup 2}P{sub 1/2} (F = 1) hyperfine component of the cooling transition that is not excited by resonant cooling light. The sideband relative intensity of a few percent proved to be sufficient to reduce the ion dwelling time in the {sup 2}S{sub 1/2} (F = 0) state to less than 10{sup -4} s and increase the cooling efficiency. (extreme light fields and their applications)

We report a single-frequency 1-W fibre laser source emitting at 1093 nm, composed of a distributed-feedback ytterbium fibre laser and fibre-optic amplifier. The laser frequency was stabilised by side-locking to a transmission peak of a Fabry — Perot interferometer, and the residual frequency noise spectrum of the laser was measured. Our results indicate that the laser linewidth can be narrowed down below 1 kHz.

A method is proposed to stabilise the frequency of a He?Ne laser with an intracavity nonlinear absorption cell by the calculated frequency of the 7?6 transition of F2(2)P(7)?3 in methane. The long-term frequency stability and reproducibility are measured for a He?Ne/CH4 laser with a telescopic cavity.

The effect of radiation reflected from an external optical element on the performance of a stabilised laser with an intracavity absorption cell is studied experimentally and theoretically taking into account the nonlinear frequency pulling to the absorption line centre.

We report on the progress in development of a highly accurate optical frequency standard based on the single ion of ytterbium-171 at the Institute of Laser Physics, Novosibirsk.