Integrated contra-directionally coupled chirped Bragg grating waveguide with a linear group delay spectrum

Due to the advantages of low propagation loss, wide operation bandwidth, continuous delay tuning, fast tuning speed, and compact footprints, chirped Bragg grating waveguide has great application potential in wideband phased array beamforming systems. However, the disadvantage of large group delay error hinders their practical applications. The nonlinear group delay spectrum is one of the main factors causing large group delay errors. To solve this problem, waveguides with nonlinear gradient widths are adopted in this study to compensate for the nonlinear effect of the grating apodization on the mode effective index. As a result, a linear group delay spectrum is obtained in the experiment, and the group delay error is halved.

Automated summary

Due to its advantages such as low propagation loss, wide operation bandwidth, continuous delay tuning, fast tuning speed, and compact footprints, chirped Bragg grating waveguide has great potential in wideband phased array beamforming systems. However, the large group delay error has hindered its practical applications. One of the main factors causing large group delay errors is the nonlinear group delay spectrum. In this study, waveguides with nonlinear gradient widths are adopted to compensate for the nonlinear effect of the grating apodization on the mode effective index, resulting in a linear group delay spectrum and a halved group delay error.