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We present the double resonance optical pumping (DROP) effect of ladder-type electromagnetically induced transparency (EIT) in the 5S1/2-5P3/2-5D5/2 transition of 87Rb atoms. When many atoms of the ladder-type atomic system are simultaneously resonant with the two laser fields, the population of one ground state can be optically pumped into another ground state through intermediate states and excited states. In this paper, we reveal that most previous results for the ladder-type EIT include the DROP effect. When the probe laser is very weak and the coupling laser is strong, we can observe the double structure transmittance spectrum, a narrow spectrum due to the EIT and a broad spectrum due to the DROP, in the 5S1/2(F=2)-5P3/2(F'=3)-5D5/2(F"=4) cycling transition.

We report experimental results on electromagnetically induced absorption spectra observed in the system which does not satisfy completely the conditions given by Lezama ͓Phys. Rev. A 59, 4732 ͑1999͔͒. We were able to observe electromagnetically induced absorption signals on all transitions in the Rb D 1 line, where F g ↔F e ϭF g Ϯ1 or F g as well as open systems. These signals were only observed in certain Rabi frequency ranges for the coupling field. Present theoretical models, which are good for the case F g ↔F e ϭF g ϩ1, considering spontaneous transfer of atomic coherences or populations have not been able to explain our experimental results obtained in both cases F g ↔F e ϭF g Ϫ1 and F e ϭF g .

Cavity-Q-driven spectral shift of lasing was observed in a cylindrical microcavity formed by rhodamine6G-doped quinoline in a capillary. The envelope of lasing spectrum showed a blueshift induced by the decreasing cavity Q of whispering gallery modes as the pump fluence increases. The thermally induced refractive index changes were measured from the shifts of individual lasing modes. The observed cavity-Q-driven spectral shift was well described by a simple dye laser model, which accounts for the dependence of cavity Q on the thermally induced refractive index change.