PURPOSE: To obtain an analog optical communication system with low noise and distortion where the transmission quality is hardly deteriorated even at the long- distance transmission by branching an electric signal into at least ≥two signals, allowing the said branch electric signal to modulate semiconductor light emitting elements having respectively different wavelengths and synthesizing each output of the said semiconductor light emitting element by means of an optical mixer or the like.
CONSTITUTION: An original signal to be transmitted is inputted from an input terminal 1 and branched by an electric signal branching device 2. Each branch signal modulates semiconductor lasers having a respectively different oscillation wavelengths at electrooptic converting sections 3, 3'. After each modulated light is synthesized at an optical mixer 4, and the light is propagated through multi- mode optical fibers 5, 7. The propagated light is converted into an electric signal at an optoelectric converting section 8 and outputted to an output terminal 9. It is necessary for the semiconductor laser to be oscillated at different wavelengths respectively. It is possible by changing the mixed crystal ratio of the laser active layer. It is desirable for the interval of wavelength to be ≤10nm taking the wavelength multiplex transmission into account.
IMOTO KATSUYUKI
HORI AKIHIRO
TANAKA KATSUKI
