Patent ID: 7149435

Claim:
A method of transmitting a high-frequency signal using an optical signal, the method comprising the steps of: generating an optical signal by modulating light wave with a signal that includes a carrier wave and a sideband wave obtained by modulating a high-frequency signal with a base-band signal in a predetermined frequency-band, a maximum frequency of which is lower than a frequency of the high-frequency signal; transmitting the optical signal; receiving the transmitted optical signal; extracting from the transmitted optical signal the carrier wave; combining the received optical signal, a first optical local component from a local light source, and a second optical local component from the local light source having a predetermined frequency differential from the first optical local component; making a frequency of the extracted carrier wave to coincide with the predetermined frequency differential; selecting a first electrical component from plural electrical components, said selected first electrical component being a frequency-shifted carrier component obtained from a combination of the modulated optical signal with a first optical local component from the first local source; selecting a second electrical component from said plural electrical components, said selected second electrical component being a frequency-shifted sideband component obtained from a combination of the modulated optical signal with a second optical local component from the second local source; and demodulating the first and second electrical components into an output high-frequency signal.