SBIR-STTR Award

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.

This Phase II proposal is concerned with the development and commercialization of novel millimeter-wave (28-100 GHz) optical fiber links capable of efficient transport and simultaneous, continuous, linear RF phase control. Efficient fiber-optic transport and RF phase control of mm-wave signals is accomplished with the same device. The results of the Phase I effort and the technical innovations discussed in this proposal will expedite the realization and deployment of optically-controlled phased-array antenna systems (CECOM) for military communications on-the-move. In the commercial arena, these low-cost fiber links are expectd to serve as an interconnecting infrastructure for fiber-fed antennas in high bandwith mm-wave wireless cellular communication systems and mm-wave cable-television systems. The patent-pending device technology is based upon injection-locking of a low-bandwidth (direct modulation bandwidth <5 Ghz) monolithic semiconductor laser at the cavity round-trip frequency. Narrowband operation is optimized at the desired mm-wave frequency by accurately cleaving the laser to the appropriate length. Due to the unique properties of optoelectronic injection-locking, continuous and dynamic control of the phase of the transmitted mm-wave signal is accomplished by simply varying the bias current into the laser. The Phase I results have generated considerable interest among Army and private sector personnel, and provides strong evidence for the successful culmination of Phase II objectives.

Benefits:
1) High performance millimeter-wave fiber-optic links with fast, continuous fine RF phase control at reduced cost and complexity for phased-array antennas. 2) Fiber optic transport of high bandwidth multimedia services for existing FCC licensed (i.e., 27.5-29.5 and 37.5-39.5 GHz) and future commercial millimeter-wave (59, 60 GHz) broadcast cable television and mobil wireless communication systems.