| 摘要 |
Optical signals emanating from the tip of an optical communication fiber can be converted, using a non-linear crystal, to signals (carrier waves) whose wavelength fall in the range of far infra-red to RF. These longer wavelength converted signals maintain the modulation of the original data. Dense fog is inherently opaque to near infra-red waves used in fiber optics communications and relatively transparent to these longer wavelengths. The modulated long wave radiation can, therefore, serve to transmit data from a fiber tip through free space under foggy (and possibly other) prevailing weather conditions. The original optical wave may be recovered by reconverting the received long wave radiation in a heterodyning process taken place in a non-linear crystal with continuous wave laser radiation of an appropriate wave length. Consequently, fiber optics communications networks can be inter-connected seamlessly through a far infra-red/RF free space link. |
