All Optical Image Reject Down-Converter
Patent application, filed 15 Mar 2001
DEPARTMENT OF THE NAVY WASHINGTON DC
Pagination or Media Count:
An optical image reject down-converter for mapping a received radio frequency RF into an arbitrary intermediate frequency range and for precluding interference between the received signals. A received radio frequency signal is down-converted into an intermediate frequency band for use by an electronic circuit in other devices. Optical light is divided into a first path and a second path. Light in the first path is transferred into an optical sideband by a first optical modulator or phase modulator. Light in a second path is converted into sidebands by a second, non-cascaded optical modulator and then passed through a tunable narrow-band optical filter which selects the desired sideband. The optical spectrum of the second path then primarily includes light at the frequency equal to the original laser frequency plus the additional sidebands. The filtered sideband is heterodyned with the light from the first path, resulting in a down-conversion to the desired intermediate frequency. Image frequencies initially present in the optical link are thereby filtered and rejected.
- Electrical and Electronic Equipment