Different configurations of a T-junction power splitter are investigated using complex-envelope alternating-direction-implicit finite-difference time-domain method. The use of reflectors on both sides of the waveguide significantly improved the performance of the T-junction waveguide after optimising the gradient of the reflectors. Cavity resonators have been added to the structure, and the transmission power on both sides of the T-junction structure is maximised. Furthermore, a photonic crystal (PhC)-based T-junction has been investigated. The results show that the use of the PhC has a major impact on the performance of T-junction.