Broadband optical delay with large dynamic range using atomic dispersion

TL;DR

This paper demonstrates a tunable all-optical delay line using atomic dispersion in rubidium vapor, achieving large, rapid delay tuning with high transmission for 10 ns pulses.

Contribution

It introduces a novel method for dynamically tuning optical delays using isotope-selective dispersion and optical pumping in rubidium vapor.

Findings

Delay of up to 40 ns for 10 ns pulses in a 10 cm vapor cell.

Rapid delay tuning over more than 40% of initial delay.

Good agreement between experimental results and numerical model.

Abstract

We report on a tunable all-optical delay line for pulses with optical frequency within the Rb $D_2$ absorption line. Using frequency tuning between absorption components from different isotopes, pulses of 10 ns duration are delayed in a 10 cm hot vapour cell by up to 40 ns while the transmission remains above 10%. The use of two isotopes allows the delay to be increased or decreased by optical pumping with a second laser, producing rapid tuning over a range of more than 40% of the initial delay at 110$^{\circ}$C. We investigate the frequency and intensity ranges in which this delay line can be realised. Our observations are in good agreement with a numerical model of the system.