Design of double-passed arrayed-waveguide gratings for the generation of flat-topped femtosecond pulse trains

This paper presents a theoretical investigation of femtosecond flat-topped pulse-sequence generation using an arrayed-waveguide grating (AWG) in a double-passed configuration. We present low-insertion-loss designs using phase-only filters designed using numerical optimization. The designs are also analyzed for robustness to fabrication errors.