Modeling of 980/1550nm PLC WDM directional coupler

For the purpose of integrating wavelength division multiplexer (WDM) into erbium doped waveguide amplifiers (EDWA), we present a 980/1550 nm planar lightwave circuit (PLC) WDM directional coupler. This silica based coupler is designed according to the fiber to waveguide coupling restriction and fabrication limitation. The coupler is designed and modeled in BeamPROP environment, utilizing finite difference beam propagation method (FD-BPM) to measure light propagation in the silica waveguide. To determine output of the coupler, the length of the coupling region, L and the edge to edge spacing between two adjacent waveguides, d are manipulated. The detailed procedures of design and optimization of the coupler is also described. The designed coupler is 11.5 mm long with 160 mum channel spacing. The simulation results show that 980 nm and 1550 nm are successfully coupled from two opposite inputs into the same output. The variation of L and d to the output intensity are plotted and analyzed. The important parameters of the coupler design are given and the advantage of the design is discussed.