Valerii F. Zakharyash

Development of an optical time scale

A time standard based on the use of an optical oscillation period of a frequencystable He−Ne laser as a time scale is first described. We obtained highly frequency-stable oscillations in the SHF range that were locked to the oscillations of a He−Ne laser stabilized to an absorption resonance in methane at 3.39 μm. A direct comparison of frequency stabilities of a rubidium standard and He−Ne/CH4 laser has been made. The absolute measurement of the frequency of the He−Ne/CH4 laser we performed gave a new value of frequency.

Comparison of frequency stabilities of the Rb standard and of the He−Ne/CH4 laser stabilized to theE line in methane

AbstractThe paper reports on the production of an optical time standard on the basis of the He−Ne laser stabilized to theE line in methane and on a comparison of its frequency stability with that of the rubidium standard. It is shown that the stability of the optical standard is better than that of the rubidium one. Frequency measurements of theE line gavevE=88373149031.2±1.2 kHz. We have also made new measurements on the frequency of the He−Ne laser stabilized to theF2(2) methane line:

Femtosecond optical clock with the use of a frequency comb

v_F = 88376181602.9 \pm 1.2kHz.

Transformation of femtosecond Ti:S laser pulses by a tapered fibers

A new stage of development of optical clocks and synthesizers is possible with the use of highly stable femtosecond lasers. Using femtosecond lasers and special optical fibres, a highly stable frequency comb covering the frequency interval up to several hundreds of THz with a spacing from 100 MHz to 1 GHz has been developed. Experimental schemes for the femtosecond optical clock based on the He-Ne/CH4 and Nd:YAG/I2 frequency standards are presented. The possibility of using tapered fibres for optical clocks and synthesizers is investigated. It is shown that, depending on their influence on the frequency characteristics of the spectral components of the transmitted radiation, tapered fibres can be used in femtosecond optical clocks and synthesizers.

Investigations of the influence of a tapered fiber on spectrum of femtosecond pulses train

The principles of precision measurement of frequency intervals in optical range with the help of femtosecond lasers are described. An experimental scheme of femtosecond optical clock is described. The characteristics of the basic elements and units of the setup are presented. The results of a broadened spectrum researches with the help of tapered fibers are reported.

Formation and distortions of the ultrashort pulse train spectrum broadened in tapered fiber

The spectral characteristics and stability of a frequency of intermode beats of a femtosecond Ti:S laser are investigated. An active method is used to obtain high stability. The frequency stability of intermode beats not lower than 5.8.10-14 rms in 100s is achieved. Possible applications of the setup, such as measurement of large frequency intervals in the optical range, creation of optical frequency synthesizers, etc. are proposed. The physical principles for the creation of an optical clock of a new type using highly stable femtosecond Ti:S laser are considered.

Investigation of Ti:S femtosecond laser radiation spectrum broadened in tapered fiber

In this paper, some results of experimental investigations of conditions of the mode-locked regime obtained by microwave pumping in a diode laser with an external cavity are presented. It was observed that the mode-locked regime is achieved at certain power levels of the microwave oscillator at pumping currents close to the generation threshold.