Tunable optical true time delay line based on chirped fiber Bragg grating

In this paper a continuously variable delay line for phased array antennas is presented. The proposed delay line operates at a single optical wavelength and it's based on a linearly chirped fiber Bragg gratings (LCFBG). Continuous true time delay can be achieved by changing the temperature along the grating region. Experimental setup uses a metallic support on which the grating is bonded. This allows to increase the temperature sensitivity of LCFBG, assuring the temperature uniformity too. Such delay line offers many advantage for beamforming application in phased array antennas where is required to simplify the architecture of these system.