Evaluation of Bragg Fibre Gratings As TTD Elements in Optical Phased Array Systems

In fibre optic TTD, the required time delay is achieved by transmitting the modulated optical carrier through an appropriate length of fiibre. Different time delays can be achieved by switching the optical carrier through various lengths of fibre. Alternatively, the time delay can be achieved using a series of Bragg grating reflectors in a single optical fibre. The wavelength selected at the tunable source corresponds to reflection from only one of the gratings introducing variable time delay (figure l )~.