Chirped fiber Bragg gratings for electrically tunable time delay lines

In this paper, a continuously variable delay line for phased array antennas is presented. The proposed delay line operates at a single wavelength and is based on properly designed linearly chirped fiber Bragg gratings. Continuous true time delay can be achieved by changing the temperature or strain along the grating region. Numerical results show that the delay line can be used for wide-band beamforming at radio frequencies up to 30 GHz with 1 ps as minimum time delay.