Nonlinear optical generation in atomic hydrogen using strong-field coupling and quantum interferences

M. Katsuragawa, G. Z. Zhang, R.S.D. Sihombing +2 more

M. Katsuragawa, G. Z. Zhang, K. Hakuta

G. Z. Zhang, M. Katsuragawa, K. Hakuta +2 more

The sum-frequency generation process using strong-field coupling and quantum interference is described systematically using atomic hydrogen both in theory and experiment. It is shown that strong coupling at the 3p-2s transition creates destructive interference to reduce the linear susceptibility at the resonant 3p\ensuremath{\leftarrow}1s transition. Simultaneously, two-photon coupling of the 2s and 1s states produces constructive interference to resonantly enhance the nonlinear susceptibility for sum-frequency generation at the 3p\ensuremath{\rightarrow}1s (Lyman-\ensuremath{\beta}) transition. Experimental results clearly demonstrate the theoretical predictions. When the Rabi frequency for the 3p-2s coupling exceeds the Doppler tail of the medium, the photoion signals on resonance are suppressed significantly because of induced transparency. The generated Lyman-\ensuremath{\beta} radiation grows rapidly by a factor of 250 at an atom density of ${10}^{15}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and interaction length of 3.5 cm, resulting in a conversion efficiency of 2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$.

Xingjun Zhang, Eddie C. Red, Albert Wynn +1 more

C. Murray, T. Pohl

K. Hakuta, G. Z. Zhang, Masayoshi Ohta +2 more

Nonlinear optical generation using electromagnetically induced transparency is demonstrated for the first time. An atomic hydrogen is used as a test atom. By applying a strong‐coupling laser field to the 3p‐2s transition, the resonant 3p‐1s transition becomes transparent with keeping the resonantly enhanced value on the nonlinear susceptibility. The generated sum‐frequency radiation at 103 nm can grow without suffering from the resonant absorption and phase‐mismatching.