Low-Loss Fiber-Optic True Time Delay Generator for RF Signal Processing and Phased Array Antenna Control (TTD).
Final technical rept. Nov 94-Oct 96,
TRW SPACE AND ELECTRONICS GROUP REDONDO BEACH CA
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The work established the viability of a fiber-optic approach for low-loss true time delay of wideband RF signals for phased-array antenna PAA beamsteering. In this approach an optical carrier modulated by the RF signal of interest is launched into a delay-line fiber composed of optical Bragg reflection gratings written holographically into the core of a single-mode fiber. The beam is steered by tuning the optical carrier wavelength for reflection from the appropriate grating. The fiber Bragg grating writing performance meets and exceeds PAA requirements. We demonstrated 1 a time delay accuracy of approximately 2 ps 20 Ps verified 2 a wavelength writing accuracy for Bragg gratings of 0.04 microns absolute, 0.01 nm relative 3 a sidelobe suppression of 50 dBe at 2 nm channels and 60 dBe at 3 nm channels. We produced a 4-bit, 16 grating true time delay element which includes an optical circulator. An analytical model, which includes chirp, was developed that predicts both the optical and RF response for the fiber optic Bragg grating.
- Electrical and Electronic Equipment
- Fiber Optics and Integrated Optics
- Electrooptical and Optoelectronic Devices