Miniature Laser Transmitter for Microwave Fiber Optic Link

Program provides capability to transfer microwave signals over fiber optic channel in 1 - 18 GHz band. Current operations require system to assess electric field within fuselage of an aircraft such as induced by radar sweep. Currently, non-fiber coaxial cable system is affected by leakage from external environment and requires holes for bulkhead connectors to be put in fuselage. Fiber optics do not pick up leakage and can be routed through existing pipes and apertures. Current baseline optical system is constrained to about 12 GHz. Development from this program extends fiber optic link bandwidth beyond 12 GHz by combining novel vertical cavity surface emitting laser (VCSEL) with electro-optic and microwave circuit and packaging technology. Proposed combination offers significant advantage in bandwidth, dynamic range, low power dissipation, and small transmitter size. At present, externally modulated lasers have large power consumption and are designed for long haul fiber optic links. Also, amplification stage connecting microwave antenna to laser module may consist of short band amplifiers in parallel. Proposed VCSEL based transmitter has smaller package, lower power dissipation and higher bandwidth for same dynamic range. Additionally, amplification stage connecting microwave antenna to laser module has a single wideband amplifier.