Coherent dark states of rubidium 87 in a buffer gas using pulsed laser light

Abstract

Abstract. The coherent dark resonance between the hyperfine levels F = 1, mF = 0 and F = 2, mF = 0 of the rubidium ground state has been observed experimentally with the light of a pulsed mode-locked diode laser operating at the D1 transition frequency. The resonance occurs whenever the pulse repetition frequency matches an integer fraction of the rubidium 87 ground state hyperfine splitting of 6.8 GHz. Spectra have been taken by varying the pulse repetition frequency. Using cells with argon as a buffer gas a linewidth as narrow as 149 Hz was obtained. The rubidium ground state decoherence cross section σ2 = 1

Autler–Townes doublet and electromagnetically induced transparency resonance probed by an ultrashort pulse train

“…The excitation scheme investigated here differs from the previous ones in that a cw coupling laser dresses the atom, which then has its excited state probed by a weak pulse train. We will refer to this excitation scheme as an EIT scheme in contrast to the CPT scheme already discussed in the literature [20][21][22][23][24]. For < γ , we will show that a subnatural linewidth feature (i.e.…”

“…By matching the train repetition rate to a subharmonic of the ground-state hyperfine splitting, CPT resonances in Doppler-broadened atomic vapours have been observed [20][21][22]. Linewidths down to 149 Hz were reported in a rubidium 87 cell with argon as buffer gas [22]. First predicted to occur by Kocharovskaya and Khanin in 1986 [23], CPT of a short pulse train results from the coherent accumulation of excitation (population and coherence) between the lower ground states of the atom [24].…”

“…By matching the train repetition rate to a subharmonic of the ground-state hyperfine splitting, CPT resonances in Doppler-broadened atomic vapours have been observed [20][21][22]. Linewidths down to 149 Hz were reported in a rubidium 87 cell with argon as buffer gas [22].…”