LIGHT WAVELENGTH DIVIDING AND MULTIPLEXING SYSTEM

摘要

PURPOSE:To realize the optical multiplex transmission with narrow wavelength intervals, by giving the optical homodyne or heterodyne wave detection to a signal underwent the light wavelength multiplexing and then separating the signal with a small frequency interval through a filter. CONSTITUTION:The diagram shows an example in which an optical multiplex transmission system using the heterodyne wave detection is applied to a signal branching transmission system. For the signal light transmitted after optical multiplexing, a part of the optical power is branched by a half mirror 8 and then multiplexed with the light given from a local oscillator Loi which has the stable oscillation with a wavelength lambdaoi through a light multiplexing device to receive an electric-optical conversion by a photodetecting element 4. The beat signal of the signal light of wavelength lambdai given from the element 4 and the local oscillation light of wavelength lambdaoi is amplified by an intermediate frequency amplifier 9 and then filtered through a BPF10 having the center frequency fi=¦C/lambdao-C/lambdaoi¦ (C: light speed) as shown in the diagram. Then a signal Si is obtained by a demodulator 11. The signal is separated by a wavelength selecting characteristic of heterodyne wave detection and an electric filter.