Abstract

We have experimentally observed light amplificaiton without inversion (AWI) in a three- level system in ruby. We believe that this observation of AWI is the first in a solid medium. The system involves R1 and R2 lines in ruby,. One of these lines was used for coupling and the other for probe. The system is therefore a V system, which has been shown to be effective for lasing without inversion. In our experiments, two tunable pulsed dye lasers were used for coupling and probe, respectively. The coupling beam has a maximum peak intensity of 420MW/cm², which corresponds to a Rabi frequency of 13 GHZ. The ruby crystal was cooled by liquid nitrogen or liquid helium. Main results includes: (1) Induced transparency was observed using coupling at either R1 or R2 wavelength. It was more significant when the system was coupled at R2 wavelength. Coupling beam intensity and detuning have strong effects on the amount of transparency. (2) Amplificaiton without inversion was observed at liquid nitrogen temperature when the system was coupled at R2 wavelength. In this case, the coupling can simultaneously create the quantum coherence and incoherently pump the population. Although this amount of population did not produce inversion, it as enough for AWI. The optimal gain was obtained by adjusting the coupling wavelength for resonance. The gain was measured by comparing the peak value with the zero absorption level of the ruby. The inversionless gain coefficient was estimated to be 0.3/cm.

© 1996 Optical Society of America