| 摘要 |
A modulated electrical signal Smod produced upon amplitude-modulating a subcarrier having a high frequency (for example, a millimeter-wave band) by a baseband signal SBB to be transmitted and a main carrier MC outputted from a light source 110 are inputted to an external optical modulating portion 120 in an optical transmitter 101. The external optical modulating portion 120 amplitude-modulates the main carrier MC by the modulated electrical signal Smod, to output a double-modulated optical signal OSdmod to an optical filter portion 130. The optical filter portion 130 passes only a component of one of sidebands included in the double-modulated optical signal OSdmod, and outputs the component to an optical fiber 140 as an optical signal OS. An optical/electrical converting portion 150 in an optical receiver 102 optical/electrical-converts the optical signal OS transmitted through the optical fiber 140, to directly obtain a baseband signal SBB. Consequently, the optical receiver 102 is constructed simply and at low cost without requiring a wideband optical/electrical converting element for optical/electrical-converting a high-frequency electrical signal and a high-frequency electrical component (a frequency converter, a demodulator, a semirigid cable or a waveguide) which is very high in cost or is difficult to process. <IMAGE> |
