Observation and theoretical simulation of electromagnetically induced transparency and enhanced velocity selective optical pumping in cesium vapour in a micrometric thickness optical cell

Abstract

Observation of electromagnetically induced transparency (EIT) and enhanced velocity selective optical pumping (VSOP) signals in a micrometric cell with cesium is reported. The line shape and non-linear features observed in the case of fluorescence in the direction parallel to the cell windows and the transmission spectra observed along the propagation direction of the probe beam show considerable differences in the spectral profile. A theoretical model based on five level optical Bloch equations is used to simulate the spectra. The Doppler convolution includes all possible orientations of atomic velocities with respect to the laser beam direction. Atoms moving nearly parallel to the windows and perpendicular to the collinear pump and probe beams have much lower Doppler shift and hence produce considerable narrowing of the Doppler background in the fluorescence spectra. The coherence decay rate is also low for such atoms as they do not meet with the cell walls. The simulated curves reproduce the observed sharp EIT peaks and enhanced broad VSOP signals for the closed probe transition in the fluorescence and absorption spectra. The observed effect of detuning of the pump frequency on the non-linear features is also reproduced by the simulation.

Forty years after the first dark resonance experiment: an overview of the COSMA project results

“…Using a micrometric thickness Cs cell, BAS-UC group recorded sharp EIT and enhanced broad VSOP signals. The observed spectra could be reproduced by a theoretical simulation with a Doppler convolution including all possible orientations of atoms with respect to the laser beam direction 27 .…”

Tailoring Sub‐Doppler Spectra of Thermal Atoms with a Dielectric Optical Metasurface Chip

“…[12][13][14] In addition, sub-natural responses such as electromagnetically induced absorption (EIA) and transparency (EIT) can be observed by controlling the state of polarization (SOP) of the pump and probe beams. [15][16][17][18][19][20][21] The SOP of light is typically adjusted using bulky optical components of cascaded polarizers and waveplates. Thus, the optical setups for SOP manipulation tend to be large and unstable.…”

A global crossover saturated-absorption spectroscopy induced by dual-frequency laser

“…It is well known that when two laser fields drive an atomic medium simultaneously, a variety of interesting nonlinear optical phenomena will occur, such as coherent population trapping (CPT) [16][17][18][19], electromagnetically induced transparency (EIT) [20][21][22][23][24][25][26], electromagnetically induced absorption (EIA) [27], amplification without inversion (AWI) [28], velocity transfer effect [29], etc. Apart from the coherence resonances such as CPT, EIT and EIA, different nonlinear resonances arising from optical pumping and saturation effects can also be observed in a multi-level system [30][31][32][33][34][35][36][37][38][39][40]. Such as velocity selective optical pumping (VSOP) produced in a Λtype system [30][31][32][33][34][35], velocity selective resonance (VSR) produced in a V-type system [36], etc.…”

“…The transmission line shape and splitting of the Doppler-free peak may be observed depending on the power and frequency of the pump laser [37,38]. Very recently such a pump-probe spectroscopic method using co-propagating laser radiations has been reported to observe EIT and VSOP dips of the Cs D 2 line [39]. Besides, the experimental observation of nonlinear resonances EIT, EIA, VSOP and VSR signals in the presence of three copropagating laser fields for the 85 Rb D 2 line was reported by Hossain et al [40].…”