Direct frequency measurement of the I_2-stabilized He–Ne 473-THz (633-nm) laser

Abstract

The absolute frequency of the 473-THz He-Ne laser (633 nm), stabilized on the g or i hyperfine component of the (127)I(2) 11-5 R(127) transition, was measured by comparing its frequency with a known frequency synthesized by summing the radiation from three lasers in a He-Ne plasma. The three lasers were (1) the 88-THz CH(4)-stabilized He-Ne laser (3.39 microm), (2) a 125-THz color-center laser (2.39 microm) with its frequency referenced to the R(II)(26) (13)C(18)O(2)laser, and (3) the 260-THz He-Ne laser (1.15 microm) referenced to an I(2)-stabilized dye laser at 520 THz (576 nm). The measured frequencies are 473 612 340.492 and 473 612 214.789 MHz for the g and i hyperfine components, respectively, with a total uncertainty of 1.6 parts in 10(10). The frequency of the i component adjusted to the operating conditions recommended by the Bureau International des Poids et Mesures is 473 612 214.830 +/- 0.074 MHz.

Learning from the time and length redefinitions, and the metre demotion

“…laser colours that step-wise matched the neon transitions, which would lead to coherent population of the 3s 2 state. This state does not even have to be inverted relative to the initial 2p4 level, as the emitted coherent red beam at 633 nm is radiated by the coherently emitting dipoles.This began the second long collaboration in Boulder, CO, with Ken Evenson's frequency-measuring team, and led eventually in 1983 to a measurement of the red 633 nm iodine-stabilized HeNe laser in terms of the 3392 nm CH 4 reference (and thereby gave the red laser's emission in hertz) [20]. Similar kinds of frequency chains were built by T. Blaney, Gordon Edwards, David Knight and colleagues at the NPL.…”

On Frequency Combs in Monolithic Resonators

“…Nondegenerate four wave mixing results in formation of a fourth photon "d" out of three photons "a", "b" and "c". The process is governed by χ (3) nonlinearity and obeys to energy and momentum conservation laws. The FWM process is observed in a 6.9 mm calcium fluorite resonator pumped with three independent lasers parked at different modes.…”

“…All these processes constitute the foundation for the Kerr frequency comb generation and associated phenomena, and are observed in optical microresonators. The third order nonlinear susceptibility χ (3) is responsible for the four-wave mixing processes [20]. In general, χ (3) is a fourth rank tensor with 81 elements [21], and each of these elements consists of a sum of 48 terms.…”

“…The third order nonlinear susceptibility χ (3) is responsible for the four-wave mixing processes [20]. In general, χ (3) is a fourth rank tensor with 81 elements [21], and each of these elements consists of a sum of 48 terms. The number of independent terms is reduced through material symmetries.…”

“…The frequencies of lasers stabilized to the 3.39 µm transition of CH 4 and the 9.33 µm and 10.18 µm transitions of CO 2 were measured with an IR frequency synthesis chain extending upwards from the Cs frequency standard [2]. The absolute frequency of a He-Ne laser (633 nm) stabilized with iodine optical transition was measured with a total uncertainty of 1.6 parts in 10 10 by comparing with a known frequency, synthesized by summing the emission frequency of three different metrology lasers in a He-Ne plasma [3]. More recently, the frequency of a 657 nm 40 Ca optical frequency standard was determined against the Cs frequency standard by a phase-coherent chain with a total relative uncertainty of 2.5 parts in 10 13 [4].…”