Electromagnetically induced transparency and optical switching in a rubidium cascade system

Electromagnetically induced transparency is observed in a mismatched-wavele ngth cascade system with a room-temperature rubidium vapor cell. A cw probe laser beam monitors the 5S(1/2) --> 5P(3/2) transition while another cw la ser couples the 5P(3/2) state to a higher excited state. The ratio of the o bserved Rabi frequencies for coupling to the 5P(3/2) --> 8D(3/2,5/2) transi tions agrees well with that predicted by use of the transition oscillator s trengths. Optical switching is demonstrated with an 80-mW coupling laser be am modulated up to 1 MHz. (C) 2001 Optical Society of America.