Theoretical study of electromagnetically induced transparency in a five-level atom and application to Doppler-broadened and Doppler-free Rb atoms

• Published in: Journal of physics. B, Atomic, molecular, and optical physics Vol. 40; no. 20; pp. 4061 - 4075
• Main Authors: Bhattacharyya, Dipankar, Ray, Biswajit, Ghosh, Pradip N
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 28.10.2007; Institute of Physics
• Subjects: Effects of atomic coherence on propagation, absorption and amplification of light; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Optics; Physics; Quantum optics; Multilevel atom; Inorganic compounds; Line shape; Electromagnetically induced transparency; Theoretical study; Density matrix; Quantum optics; Diatomic molecules; Cold atom; Doppler effect; Allowed transition; Pump probe spectrometry; Line broadening; Group velocity; Rubidium Molecules; Rubidium Atoms
• ISSN: 0953-4075; 1361-6455
• DOI: 10.1088/0953-4075/40/20/008

We report theoretical studies of a Lambda-type five-level atomic system. The density matrix equations are set up and solved numerically to obtain the probe absorption line shape of Rb D2 transitions for cold (Doppler-free) and room temperature (Doppler-broadened) atoms. Simulated spectra for Doppler-broadened systems lead to four velocity-selective dips along with an electromagnetic induced transparency (EIT) peak as observed earlier from the co-propagating pump-probe spectroscopy of Rb D2 transitions. Effects of pump power and spontaneous decay rate from the upper levels on the simulated spectra are also studied. For cold atoms a very pronounced EIT peak is observed when the pump frequency is on resonance with one allowed transition. We find that lower pump power leads to a much sharper EIT signal in this case. A simulated dispersion curve shows a rapid variation of the refractive index that may lead to a sharp reduction of the group velocity of photons.