Compact, Ti:sapphire-based, methane-stabilized optical molecular frequency comb and clock

Abstract

A compact optical clock and frequency comb system is presented, based on a 1 GHz octave spanning Ti:sapphire laser referenced to the F

Visible wavelength astro-comb

“…We have chosen frequency doubling of a broadband Ti:Sapphire laser, Fig. 3, to provide a source comb at 400 nm, because we have previously [19] constructed stable and high power Ti:Sapphire lasers that are capable of operating unattended on day long timescales. Absolute referencing of such lasers is also more direct than with other systems, as Ti:Sapphire lasers can generate optical spectra directly from the laser cavity that cover more than one octave; this allows direct access to the carrier envelope offset frequency, f ceo , control of which is required if all optical frequencies from the frequency comb are to be known.…”

Application of the methane saturated dispersion resonance near 2.36μm over the temperature range of 77–300 K for optical frequency standards

“…39 µm have 5 been shown to have remarkable characteristics for the frequency stabilization of a He-Ne laser [3,4,5]. The frequency of the 3.39-µm He-Ne laser stabilized by methane lines was measured using several methods [6,7]; as a result, an optical frequency standard was designed [8,9,10,11,12] and several approaches for optical frequency combs stabilization were proposed [13,14,15,16]. To date, 10 much research has considered the methane P(7) line of the ν 3 band parameters at 3.39 µm [17,18]; however there are a number of lines in the mid-IR region that are free from magnetic hyperfine structures that have better prospects for use in laser frequency stabilization.…”

“…The frequency of the 3.39-µm He-Ne laser stabilized by methane lines was measured using several methods [6,7]; as a result, an optical frequency standard was designed [8,9,10,11,12] and several approaches for optical frequency combs stabilization were proposed [13,14,15,16]. To date, 10 much research has considered the methane P(7) line of the ν 3 band parameters at 3.39 µm [17,18]; however there are a number of lines in the mid-IR region that are free from magnetic hyperfine structures that have better prospects for use in laser frequency stabilization. The development of cw tunable solidstate lasers based on crystals of A 2 B 6 compounds doped with divalent ions 15 of transition metals [19,20,21] solved the problem of choosing appropriate lines [22,23,24].…”

^87Rb-stabilized 375-MHz Yb:fiber femtosecond frequency comb

“…While modelocked Yb:fiber lasers are available at repetition frequencies approaching 1 GHz [7], achieving pulses with the sufficiently short durations and high peak powers needed to generate a coherent octave-spanning spectrum becomes very difficult; conversely, the power per comb mode increases with higher repetition rates, implying that an approach based on a linear stabilization technique should be favorable. Heterodyne beats between stabilized CW lasers and adjacent comb teeth have previously been used to lock the offset frequency of Ti:sapphire combs using a 1064-nm iodine-referenced Nd:YAG laser [8], a 822-nm cesiumreferenced external cavity diode laser (ECDL) [9], a 3.39-µm methane-referenced HeNe laser [10] and a 698-nm cavity-stabilized ECDL [11]. Similar techniques were used to stabilize Er:fiber combs to a 780-nm Rb-referenced ECDL [12] and to two Rb resonances based on electromagnetically induced transparency absorption and two-photon absorption [13].…”