| 摘要 |
PURPOSE:To attain wireless transmission of a high definition animation or the like by providing a wavelength tuning means controlling a wavelength of a local oscillating light so that a difference between a reference wavelength of a signal light and the wavelength of the local oscillation light is a prescribed wavelength to the transmitter. CONSTITUTION:A sender side is made up of a wavelength variable semiconductor laser 10 generating local oscillating lights whose reference wavelengths are lambda0, lambda1 while switching them digitally, a control circuit 11 controlling its oscillating intensity and the wavelengths, and a laser beam radiation window 12. A receiver side is provided with a polarization filter 13 converting a signal light into a linearly polarized light, a filter 14 cutting off most of in-room lighting and the sun ray and filtering only a wavelength region of the signal light, a lens 15 collecting the signal light, a reference wavelength coherent light local oscillating semiconductor laser 16, a light receiving element 17 mixing the lights and detecting a beat signal of them, and a signal processing circuit 18 amplifying and shaping its output and demodulating the signal. The signal light and the local oscillation light are mixed, the mixed light is photoelectric-converted, its AC component is frequency-discriminated and the signal is reproduced from its output in this way. |
