Lineshape Asymmetry for joint CPT and three photon N resonances

TL;DR

This paper investigates the asymmetry in lineshapes caused by joint CPT and N resonances due to laser modulation sidebands, with implications for atomic clock accuracy.

Contribution

It provides both experimental and theoretical analysis of lineshape asymmetry in joint CPT and N resonances relevant to atomic frequency standards.

Findings

Lineshape asymmetry arises from modulation sidebands in laser light.

Joint CPT and N resonances significantly distort resonance lineshapes.

Results are relevant for improving miniaturized atomic clocks.

Abstract

We show that a characteristic two photon lineshape asymmetry arises in coherent population trapping (CPT) and three photon (N) resonances because both resonances are simultaneously induced by modulation sidebands in the interrogating laser light. The N resonance is a three-photon resonance in which a two-photon Raman excitation is combined with a resonant optical pumping field. This joint CPT and N resonance can be the dominant source of lineshape distortion, with direct relevance for the operation of miniaturized atomic frequency standards. We present the results of both an experimental study and theoretical treatment of the asymmetry of the joint CPT and N resonance under conditions typical to the operation of an N resonance clock.