Doppler-free coherent-control spectroscopy with a colliding pair of shaped pulses

TL;DR

This paper demonstrates a novel ultrafast coherent-control spectroscopy technique that uses shaped counter-propagating pulses to resolve fine-structure two-photon transitions in atomic rubidium, achieving spatially selective excitation.

Contribution

The work introduces three pulse-shaping solutions combining amplitude and phase programming to selectively induce two-photon transitions in rubidium vapor.

Findings

Successful resolution of fine-structure two-photon transitions

Agreement between experimental results and theoretical analysis

Spatially selective excitation of atomic transitions

Abstract

We demonstrate the use of the ultrafast spatial coherent-control method to resolve the fine-structure two-photon transitions of atomic rubidium. Counter-propagating ultrafast optical pulses with spectral phase and amplitude programmed with our optimized solutions successfully induced the two-photon transitions through $5S_{1/2}$-$5P_{1/2}$-$5D$ and $5S_{1/2}$-$5P_{3/2}$-$5D$ pathways, both simultaneously and at distinct spatial locations. Three different pulse-shaping solutions are introduced that combine amplitude shaping, which avoids direct intermediate resonances, and phase programming, which enables the remaining spectral components to be coherently interfered through the targeted transition pathways. Experiments were performed with a room-temperature vapor cell, and the results agree well with theoretical analysis.