Millimeter Wave (28-100 GHz) Fiber-Optic Links with RF Phase Control for Phased-Array Antennas

This effort proposes to investigate novel optical transmitters with RF phase control for narrowband millimeter-wave (28-100 GHz) fiber-optic links using direct modulation of semiconductor lasers. Efficient fiber-optic transport and simultaneous, continuous phase control of the transmitted millimeter-wave signal is accomplished with the same device. This allows military phased-array systems to exploit the advantages of fiber while reducing system cost and complexity. Furthermore, these fiber links can provide high bandwidth services in present and future cable television and wireless communication systems. Since this work is of obvious commercial and military interest it falls into a genuine "dual-use" category. The innovative device is a split-contact monolithic semiconductor laser, cleaved to a length such that the laser round-trip cavity resonance occurs at the desired millimeter-wave frequency. Continuous control of the phase of the transmitted millimeter-wave frequency. Continuous control of the phase of the transmitted millimeter-wave signal is accomplished by simply varying the bias current into the laser. This task has been demonstrated at lower frequencies (1-7 GHz) using commercially available compact-disk self-pulsing lasers. The prior success with self-pulsing lasers and the recent implementation of millimeter-wave optical transmitters using monolithic semiconductor lasers provide strong evidence for successful completion of Phase I of this effort.