Stabilization of reproducibility of frequencies of He-Ne lasers at 0.63 µ

An Optical Clock Based on a Single Trapped 199 Hg + Ion

“…Fundamental ideas and technical developments principally in three areas have brought us to the point where we are now able to demonstrate an optical frequency standard representative of clocks of the future: (i) the idea (25,26) and demonstration of laser cooling of atoms (27,28), (ii) the frequency stabilization of lasers (29)(30)(31)(32), and (iii) the concept (33) and demonstration (5-10) that femtosecond mode-locked lasers combined with nonlinear fibers can provide a simple, direct, and phasecoherent connection between radio frequencies and optical frequencies. Although most of these concepts have existed for some time, and preliminary demonstrations of optical clocks have even been made (34)(35)(36), only now have the techniques and tools advanced to the levels required for optical frequency standards to move beyond the benchmark results of the microwave standards.…”

Pages from the history of quantum electronics research in the Soviet Union

“…Among many pioneering works, done by scientists of this institute in quantum electronics and laser physics, investigations resulting in the creation of a new direction in optical spectroscopy-nonlinear super high-resolution laser spectroscopy-should be emphasized especially. They proposed and realized several methods for nonlinear laser spectroscopy: saturated absorption [64,65], two-photon absorption in standing wave fields [66], separated optical fields [67], and others (see [68]). These methods became basic ones for creating ultra stable laser frequency standards (see the review paper [69]).…”