Design and simulation of phase shifter based on multimode interference in photonic crystal waveguide

This paper proposes a new design for a pi-phase shifter and two pi/2-phase shifters, which are based on a two-dimensional rods-in-air photonic crystal waveguide. The proposed devices have been designed using both triangular and square lattice photonic crystal structures. Notably, these phase shifters do not require any external energy source to operate. To calculate the band diagram of the PhC, the plane wave expansion method was utilized, while finite-difference time-domain simulation methodology was used to estimate and examine the performance of the proposed phase shifters. The simulation results demonstrate that the proposed pi-phase shifter can achieve a bandwidth of 1.5THz, whereas the pi/2-phase shifters, designed on triangular and square lattice can achieve bandwidths of 1.9THz and 1.35THz, respectively. Due to their straightforward design structure and energy independence, these devices are well-suited for future generations of all-optical photonic integrated circuits.