We have found that room-temperature HF gas at millitorr pressures, optically pumped to produce a total inversion at a rotational transition in the $v=1$ vibrational state, emits a superradiant pulse with ringing after a considerable delay (\ensuremath{\sim} microseconds). A semiclassical analysis shows that for a high-gain system the pulse evolution is determined by a single parameter ${\ensuremath{\tau}}_{R}$, and that inhomogeneous broadening is unimportant. Close agreement between theory and experiment is obtained.We have found that room-temperature HF gas at millitorr pressures, optically pumped to produce a total inversion at a rotational transition in the $v=1$ vibrational state, emits a superradiant pulse with ringing after a considerable delay (\ensuremath{\sim} microseconds). A semiclassical analysis shows that for a high-gain system the pulse evolution is determined by a single parameter ${\ensuremath{\tau}}_{R}$, and that inhomogeneous broadening is unimportant. Close agreement between theory and experiment is obtained.

Physical Review LettersFeb 19, 1973765 citations

Dynamics of superradiant emission

Joseph H. Eberly, Nicholas E. Rehler

Physics Letters AApr 1, 196948 citations

Superradiance of High Density Frenkel Excitons at Room Temperature

H. Z. Wang, Xiuyuan Zheng, F. L. Zhao +2 more

Superradiance of high density Frenkel excitons in an $R$ -phycoerythrin single crystal is observed at room temperature for the first time. No fluorescence is observed except the emission at the sharp exciton band when the superradiance of excitons occurs, and the higher the pump density, the sharper the emission bandwidth. A redshift and a blueshift are observed at the rise time and the fall time of the emission pulse, respectively. The experimental results also imply deformed-boson properties of high density Frenkel excitons.Superradiance of high density Frenkel excitons in an $R$-phycoerythrin single crystal is observed at room temperature for the first time. No fluorescence is observed except the emission at the sharp exciton band when the superradiance of excitons occurs, and the higher the pump density, the sharper the emission bandwidth. A redshift and a blueshift are observed at the rise time and the fall time of the emission pulse, respectively. The experimental results also imply deformed-boson properties of high density Frenkel excitons.

Physical Review LettersMay 15, 199526 citations

Optical amplification and gain dynamics of cavity-free lasing of argon pumped by ultraviolet femtosecond pulses

Chengxuan Zhuang, Xiang Zhang, Qi Lu +1 more

Argon gas excited by resonant femtosecond ultraviolet pulses gives rise to cavity-free lasing emission in the near-infrared (NIR) range. Here we reported on a pump-probe study of the optical gain of this lasing phenomenon. With the injection of an external seeding pulse, the forward signal was significantly enhanced, confirming the existence of optical gain. The temporal dynamics of the optical gain were characterized by a time-resolved measurement. It was found that the optical gain decays on a time scale of ∼ 10 ps and it does not present a significant dependence on the gas pressures. Moreover, the intensity of the forward NIR emission signal shows a linear dependence on the gas pressure. These features suggest that the nature of this forward NIR radiation is amplified spontaneous emission, not superradiance when multiple-photon resonant excitation is involved.Argon gas excited by resonant femtosecond ultraviolet pulses gives rise to cavity-free lasing emission in the near-infrared (NIR) range. Here we reported on a pump-probe study of the optical gain of this lasing phenomenon. With the injection of an external seeding pulse, the forward signal was significantly enhanced, confirming the existence of optical gain. The temporal dynamics of the optical gain were characterized by a time-resolved measurement. It was found that the optical gain decays on a time scale of ∼ 10 ps and it does not present a significant dependence on the gas pressures. Moreover, the intensity of the forward NIR emission signal shows a linear dependence on the gas pressure. These features suggest that the nature of this forward NIR radiation is amplified spontaneous emission, not superradiance when multiple-photon resonant excitation is involved.

Optics ExpressApr 25, 20221 citation

Superradiant amplification in an optically dense gas

Jamal T. Manassah, Barry M. Gross

Optics CommunicationsNov 1, 199725 citations

We have found that room-temperature HF gas at millitorr pressures, optically pumped to produce a total inversion at a rotational transition in the

v=1

vibrational state, emits a superradiant pulse with ringing after a considerable delay (\ensuremath{\sim} microseconds). A semiclassical analysis shows that for a high-gain system the pulse evolution is determined by a single parameter ${\ensuremath{\tau}}_{R}$, and that inhomogeneous broadening is unimportant. Close agreement between theory and experiment is obtained.

Superradiance of high density Frenkel excitons in an

R

-phycoerythrin single crystal is observed at room temperature for the first time. No fluorescence is observed except the emission at the sharp exciton band when the superradiance of excitons occurs, and the higher the pump density, the sharper the emission bandwidth. A redshift and a blueshift are observed at the rise time and the fall time of the emission pulse, respectively. The experimental results also imply deformed-boson properties of high density Frenkel excitons.