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A Novel Photonics Beam-Former Using Tunable Fiber Laser Array for Phased Array Antenna
Jianling Yang, Swee Chuan Tjin and Nam Quoc Ngo

A true-time-delay system for wideband continuous phased array beam-forming using an array of wavelength tunable fiber lasers with equally increased or decreased wavelength spacing is proposed and demonstrated. The wavelength of each laser source is determined by the fiber Bragg grating incorporated in the laser array cavity and tuned by applying strain. To simultaneously achieve N tunable lasers, N fiber Bragg gratings are used. To ensure a wavelength tuning with equally increased or decreased wavelength spacing, the N fiber Bragg gratings are mounted onto an organic plastic plate with angles between adjacent gratings such that the tuning forces applied to the gratings experience an equal force increment. Time delays with equally increased or decreased time delay difference for the equally spaced wavelengths are obtained when the modulated lightwaves are reflected at different locations on a linearly chirped grating. A four-channel chirped-grating-based true-time-delay system using the proposed light source for continuous beam steering was constructed and demonstrated. Continuous beam steering at the microwave frequency up to 18 GHz has been achieved.

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