Atomic Frequency Reference Based on 4S1/2−4P1/2 Transitions in Potassium Vapor Placed in a Nanocell

Abstract

Sub-Doppler resonances formed by scanning the laser frequency in the region of the 4S_1/2 → 4P_1/2 transition at a wavelength of 770 nm in K atomic vapors placed in a nanocell were studied. Sub-Doppler resonances located at the unshifted atomic transitions F_g = 1, 2 → F_e = 1, 2 were formed in the transmission spectrum for atomic vapor thicknesses L = λ/2 = 385 nm and L = λ = 770 nm. The resonance amplitudes observed in the nanocell were proportional to the probability amplitudes of the corresponding transitions. It is shown that a nanocell with a vapor thickness L = λ = 770 nm could be used as a convenient frequency reference tied to the unshifted frequencies of the atomic transitions. The advantages of the proposed frequency reference over a commonly used frequency reference based on saturated absorption techniques were demonstrated.