We propose a novel and compact broadband 1×3 beam splitter (BS), which is based on optical tunneling between neighbor and parallel waveguides; thus, it is used to couple energy from one waveguide to another. This device consists of three parallel planar waveguides, in which the energy is transferred in a coherent fashion, so that the direction of propagation is maintained. For complete energy transfer to occur between the neighbor waveguides, they must have identical propagation constants. Thus, indices and height of the waveguide layers are controlled very carefully to provide matching propagation constants. The total length of BS is only about 7 μm. The simulation and analysis show that the BS for transverse magnetic (TM) light at a wavelength of 1.55 μm is designed to split incident light into three beams, whose power is 20, 34, and 18%, respectively. The wavelength bandwidth reaches up to 52 nm with an increase in wavelength from 1.49 to 1.542 μm, in which the maximum power difference of three output ports is less than 10%; moreover, the minimum is nearly 0. BS designed here particularly suits for optical communication and optical information processing.