Compact and broadband 2×2 3 dB optical power splitter based on bricked subwavelength gratings

We design and experimentally demonstrate a compact and broadband 2 × 2 3 dB optical power splitter engineered by bricked subwavelength gratings (BSWG). In this work, 3D finite difference time domain (FDTD) and particle swarm optimization (PSO) methods are combined to optimize the power splitter. The simulation results show that the coupling length is 6.11 μm, the excess loss (EL) is lower than 0.6 dB and the power splitting ratio is better than 3 ± 0.72 dB within the wavelength range from 1450 nm to 1650 nm for the TE mode. Experimental results show EL < 0.77 dB and power splitting ratio better than 3 ± 0.74 dB in a bandwidth of 100 nm (1480 nm–1580 nm, limited by the laser tuning range and grating coupler). Additionally, the minimum feature size of the BSWG is 139 nm, which is larger than that of the conventional SWG (∼100 nm), thereby easing fabrication challenges.