PHYSICAL REVIEW A 84, 033821 (2011) Polarization dependence of double-resonance optical pumping and electromagnetically induced transparency in the 5 S 1/2 -5 P 3/2 -5 D 5/2 transition of 87 Rb atoms Han Seb Moon 1,* and Heung-Ryoul Noh 2,† 1 Department of Physics, Pusan National University, Busan 609-735, Korea 2 Department of Physics, Chonnam National University, Gwangju 500-757, Korea (Received 8 February 2011; published 15 September 2011) The polarization dependence of double-resonance optical pumping (DROP) in the ladder-type electromagnet- ically induced transparency (EIT) of the 5S 1/2 -5P 3/2 -5D 5/2 transition of 87 Rb atoms is studied. The transmittance spectra in the 5S 1/2 (F = 2)-5P 3/2 (F ′ = 3)-5D 5/2 (F ′′ = 2,3,4) transition were observed as caused by EIT, DROP, and saturation effects in the various polarization combinations between the probe and coupling lasers. The features of the double-structure transmittance spectra in the 5S 1/2 (F = 2)-5P 3/2 (F ′ = 3)-5D 5/2 (F ′′ = 4) cycling transition were attributed to the difference in saturation effect according to the transition routes between the Zeeman sublevels and the EIT according to the two-photon transition probability. DOI: 10.1103/PhysRevA.84.033821 PACS number(s): 42.50.Gy, 32.10.Fn, 32.80.Xx, 32.80.Qk I. INTRODUCTION In high-resolution spectroscopy, atomic coherence and optical pumping play an important role in an optical medium with light [1]. The atomic coherent phenomena are coun- terintuitive and caused by quantum interference between the atomic states. Electromagnetically induced transparency (EIT) is an example of atomic coherent phenomenon [2–4]. Using the characteristics of EIT with a narrow spectral width and transparency, EIT has been applied to potentially important areas, including light storage [5,6], precision magnetometers [7,8], and quantum optics [9–11]. Although many optical pumping phenomena may be understood intuitively by the rate equation described as the change in the population by optical pumping, the spontaneous process due to optical pumping affects the decay of the atomic coherence significantly. The spectrum can occur not only through quantum interference due to the atomic coherence, but also via a population change in the state that results from optical pumping. The EIT spectrum also includes an optical pumping effect by the coupling laser. In the case of the atoms in the -type atomic system, composed of two ground states and a common excited state, most of the population in one ground state may be optically pumped into another ground state by single-photon resonance. The role of optical pumping in the EIT spectrum of an atomic vapor has already been discussed [12]. The ladder-type atomic system represents an excitation from a ground state to a high-lying state via a common intermediate state, as shown in Fig. 1. Before lasers were developed, Bitter proposed to detect very small changes of Zeeman sublevels using the optical detection of radio fre- quency resonance [13]. Double-resonance spectroscopy has already been applied to the study of atomic transitions [14]. In the case of a ladder-type atomic system with a double- resonance transition [15–17], there is optical pumping in the ladder-type atomic system due to the so-called double- resonance optical pumping (DROP) phenomenon [18–20]. * hsmoon@pusan.ac.kr † hrnoh@chonnam.ac.kr The magnitude of optical pumping is proportional to a two- photon transition probability and the frequency of the optical pumping is under the condition of the two-photon resonance similar to the two-photon atomic coherence. It was reported that the ladder-type EIT is not free from the optical pumping effect, which was more serious in the ladder-type EIT than in the -type EIT [20]. As is well known, the atomic coherence and optical pumping affect the polarization of the interacting lasers with atoms significantly due to the different transition probabilities according to the laser polarization and hyperfine states. Although the DROP effect on the ladder-type EIT has been reported [18], the dependence of the polarization of the lasers between the DROP and EIT in a ladder-type atomic system has not been reported. Also, the transmittance spectrum due to EIT and saturation effect according to the laser’s polarization has never been investigated in the 5S 1/2 (F = 2)- 5P 3/2 (F ′ = 3)-5D 5/2 (F ′′ = 4) cycling transition. In the present work we study the influence of polariza- tion combination on EIT, DROP, and saturation effect in a5S 1/2 -5P 3/2 -5D 5/2 ladder-type system with use of room- temperature rubidium atoms in a vapor cell. The relative intensity and the spectral-shape features of the transmittance spectra in the 5S 1/2 (F = 2)-5P 3/2 (F ′ = 3)-5D 5/2 (F ′′ = 4) cycling transition were investigated with various polarization combinations of the laser. We also discuss how polarization affects the spectra. In addition, the transmittance spectra were simulated by considering the two-photon transition probability and optical pumping. II. EXPERIMENTAL SETUP Figure 1 shows the energy-level diagram of the 5S 1/2 -5P 3/2 -5D 5/2 transitions of 87 Rb atoms. The 5S 1/2 -5P 3/2 transition is resonant on the probe laser at 780 nm and the 5P 3/2 -5D 5/2 transition is resonant on the coupling laser at 776 nm. The natural line widths of the 5P 3/2 and 5D 5/2 states are approximately 6.0 MHz and 0.67 MHz, respec- tively. When the atoms are resonant with the fields of the coupling and probe lasers, the population of the 5S 1/2 (F = 2) state may be depleted because many atoms excited to the 5D 5/2 states (F ′′ = 2,3) can be optically pumped to the 033821-1 1050-2947/2011/84(3)/033821(5) ©2011 American Physical Society