Design of adjustable T-shaped and Y-shaped photonic crystal power splitters for TM and TE polarizations

Abstract

In this paper, new topologies for realization of photonic crystal optical power splitters for TE and TM modes are proposed. The presented structures can be used for dividing input power with a desired ratio to output ports. The central input wavelength is designed for 1550 nm. To obtain wide-bandwidth power splitters for TE and TM modes, modified Y-shaped and T-shaped photonic crystal junctions are used. A triangular lattice of air holes and a square lattice of rods are used for Y-shaped and T-shaped platforms, respectively. For analyzing these structures, plane wave expansion and finite difference time domain methods are used. Simulation results show that the T-shaped splitter has a bandwidth equal to 51 nm, while the bandwidth of the Y-shaped structure is 126 nm. One of the advantages of the presented topologies is that the power share directed towards each output port can be determined by changing the radii of some specified rods and holes in their structures. For the designer to calculate the optimum radii of the holes based on his desired power ratio, some formulas are presented. Compared to the tunable power splitters based on directional couplers, this method provides much wider bandwidth and a more linear power ratio function.