Demonstration of super‐Gaussian apodized linearly chirped fiber Bragg grating for efficient beam steering in Ku‐band applications

Abstract

This paper demonstrates a photonics-based wideband TTD beamforming network employing super-Gaussian apodised chirped fibre Bragg grating (SGFBG) of different length (each having a central wavelength of 1550 nm) such as 5, 4.5, 4, 3.5, 3, 2.5, 2 and 1.5 cm as well as varying chirp rate, which can be used as variable TTD lines for controlling the radiation angle of PAA (the main lobe radiated by the PAA can be steered squint-free between 0 ° and ± 69 ° ) suitable for continuous beamforming at microwave frequencies in Ku-band (12–18 GHz). The experimental demonstration shows the effect of change in laser wavelength on delay incurred within the reflected light from the SGFBG. This delay in the modulated optical signal will be converted into delayed microwave signal feed to a respective element of PAA after passing through the photodetector. Finally, the time-delayed microwave signal feeded to each element of PAA will be responsible for tilt in microwave signal compared to the horizontal direction. The novelty of the proposed SGFBG as compared to linearly chirped fiber Bragg grating (LCFBG) is in terms of reduction in ripples in the delay spectrum which will lead to exact delay introduction in the optical signal.