Abstract

Transferring the principle of phased array antennas from the microwave regime into optics is not straightforward due to the small wavelengths involved.^[1] Path differences between the wavefronts leaving the individual subantennas of an array have to be actively controlled to within a fraction of the wavelength.^[2] To this end we developed a phasing concept using a common reference wavefront of a so called pilot beam, which is slightly offset in frequency. By heterodyning the pilot beam with representative samples of the individual subwavefronts, the optical phases are transformed into electrical phases at intermediate frequency signals. They permit phasing via heterodyne phase-locked loops.

© 1992 IQEC