High-Efficiency Optical Wavelength Converter via Resonant Four-Wave Mixing
Jia-Kang Lin (林家慷)1*, Jz-Yuan Juo (卓至原)1, Ite A. Yu (余怡德)2, Yong-Fan Chen (陳泳帆)1
1Department of Physics, National Cheng Kung University, Tainan, Taiwan
2Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
* presenting author:Jia-Kang Lin, email:iq625678@yahoo.com.tw
We study high-efficiency optical wavelength converters based on N-type resonant four-wave mixing (FWM) processes. Theoretical calculations show that 50% optical energy is dissipated by the vacuum fluctuation, and the maximum efficiency of wavelength conversion saturates at 25%. By using two spatially varied laser fields, the dissipation by vacuum fluctuation could be effectively suppressed. Theoretical model shows that this improved scheme can achieve a conversion efficiency of 96% by a medium with an optical depth (OD) of 240. With this novel resonant FWM scheme, we demonstrate the first experimental observation of wavelength conversion of light from 780 nm to 795 nm with 43% conversion efficiency at OD of 19 in cold 87Rb atoms.

Keywords: Four-wave mixing, FWM, EIT